14: WESTWARD

EXPANSION

Catherine Locks, Sarah Mergel, Pamela

Roseman, Tamara Spike & Marie Lasseter
George State Universities
CHAPTER OVERVIEW
14: WESTWARD EXPANSION
learning outcomes

After completing this chapter, you should be able to:

Trace the expansion processes that completed the continental United States.
Explain the underlying causes of the expansion of the United States.
Describe the legacies of expansion.

The expansionist movement in the United States gained tremendous momentum in the 1840s. The movement, coined “manifest destiny”
in the mid-1840s, justified expansion with a sense of mission and purpose, viewing American expansion as inevitable, just, and divinely
foreordained. This expansion led to the addition of Texas and Oregon to the Union and was an underlying cause of war with Mexico,
which resulted in the acquisition of vast territories in the Southwest, including the prize of California.

However, expansion came at a price. The Mexican-American War further incited resentment of the United States by not only Mexico,
but also the region of Latin America. In the aftermath of the war, tensions grew between the American and Mexican populations of
Texas and California as Hispanics were pushed further and further out of the dominant society, dispossessed of their land, and politically
disenfranchised in the new states of Texas and California. Westward expansion also led to increasing hostilities between the United
States and Native Americans, resulting in a series of disturbances, massacres, and wars. Finally, the expansionist movement further
ignited the debate over slavery in the wake of the Missouri Compromise.

14.1: WESTWARD EXPANSION AND MANIFEST DESTINY

14.2: THE MEXICAN-AMERICAN WAR
14.3: CONCLUSION
14.4: CRITICAL THINKING EXERCISES
14.5: KEY TERMS
14.6: CHRONOLOGY

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14.1: Westward Expansion and Manifest Destiny
The American expansionist movement did not begin with Manifest Destiny and the push westward in the 1840s. Americans
had been pushing boundaries since the colonial era, most notably across the Appalachian Mountains. Jefferson set the stage for
expansionism with the Louisiana Purchase; the movement grew in the 1830s with the Indian Removal program under Jackson,
“freeing” land east of the Mississippi for the expanding population. At the turn of the century, the overwhelming majority
lived east of the Appalachian Mountains; just fifty years later, about half of all Americans lived west of the mountains, a
tremendous demographic shift.
The rapid western expansion of the 1840s resulted in great part from demographic, economic, and political pressures. The
population of the United States grew rapidly in the period from 1800-1850, rocketing from about five million to over twenty
million in a fifty-year period. Americans were increasingly land-hungry as populations grew. Throughout many of the
overworked farms of the east, soil fertility was declining, making the cheap land of the west more and more attractive.
Politically, many feared that if the United States did not occupy the West, then the British would. Some reasoned that
westward expansion would counterbalance the increasingly industrialized and urbanized northeast, assuring that the republic
of the United States would continue to be rooted in the ideals and values of Jefferson’s yeoman farmer. Expansion deeply
influenced U.S. foreign policy; to the south, tensions arose with Mexico as thousands of Americans immigrated into the
Mexican state of Coahuila y Tejas, hereafter referred to as Texas. Expansion was also deeply economically motivated. For
example, Eastern merchants wanted control of west coast ports to trade with Asia. Overall, many Americans envisioned the
same end, even though they favored expansion for different reasons; many, however, came to equate the idea of “spreading
freedom” with spreading the United States.
The westward expansion movement continued in the 1840s. During this period, the concept of Manifest Destiny arose to give
a religious and cultural justification to American expansion across the continental United States. Millions of Americans
professed the belief that the destiny of the United States was to spread democratic institutions “from sea to shining sea.”
Manifest Destiny asserted that Americans would expand to the limits of North America, taking political and economic control
of the continent. In the process, the inhabitants of North America, including Indians and Mexicans, would be Americanized.
Any attempt to resist would be forcibly extinguished. Some would even argue that, in effect, God had chosen Americans to
control the Western Hemisphere. These viewpoints are evident in the speech of Senator Thomas Hart Benton, one of the
leading proponents of Manifest Destiny:
I know of no human event, past or present, which promised a greater, and more beneficent change upon the earth than
the arrival of…the Caucasian race…It would seem that the white race alone received the divine command, to subdue
and replenish the earth! for it is the only race that has obeyed it—the only one that hunts out new and distant lands, and
even a New World, to subdue and replenish…the Caucasian race now top[s] the Rocky Mountains, and spread[s] down
the shores of the Pacific. In a few years a great population will grow up there, luminous with the accumulated lights of
the European and American civilization...The Red race has disappeared from the Atlantic coast: the tribes that resisted
civilization met extinction… For my part, I cannot murmur at what seems to be the effect of divine law… Civilization,
or extinction, has been the fate of all people who have found themselves in the track of advancing Whites, and
civilization, always the preference of the Whites, has been pressed as an object, while extinction has followed as a
consequence of its resistance.
However, the issue was certainly not that simple. The issue of expansion raised challenging and hotly-debated questions that
were taken up by both the American government and the American population. Was expansionism moral, and moreover, could
a government accept and even promote expansion through moral action, or were the two mutually exclusive? Would the nation
fundamentally change with the incorporation of distant lands and new populations (perceived by many as “unable to
assimilate” into the U.S. population)? Would unchecked expansionism threaten American military and economic security?
Was the expansion of the United States synonymous with the expansion of freedom? Finally, how was the growing nation to
expand without upsetting the precarious balance between free and slaveholding states? In the first half of the nineteenth
century, the Southwest Ordinance of 1790 mandated the Ohio River as a dividing line: states to the south of the river would be
open to slavery. Consequently, the area north of the river was largely characterized by family farms and free labor, and to the
south, largely characterized by slave labor. As the expansionist movement grew in the 1840s, the nation struggled to maintain
a stalemate of sorts as territories were incorporated into the nation as states. By 1850, seven states (California, Illinois, Indiana,
Iowa, Maine, Michigan, and Wisconsin) had entered the union as free states, and six as slaveholding states (Alabama,

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Arkansas, Florida, Mississippi, Missouri, and Texas). As the concept of manifest destiny developed throughout the 1840s, it
became increasingly apparent that it was for white Americans only, not only because of the spread of slavery as a part of
westward expansion, but also because of American attitudes and policies towards the Indian and Mexican populations of areas
such as Texas and California. Manifest destiny also became a justification for the aggressively expansionist policies of
President James Polk.

14.2.1: Texas
The first movement of American settlers outside of the boundaries set by the Missouri Compromise was into the Mexican
province of Texas, an area that had been sparsely populated since the early colonial era. As a newly independent country,
Mexico was in a politically tumultuous state. Agustín I, emperor of the short-lived Empire of Mexico (1821-1823), hoped to
populate the land that had been home to mostly Indians and Franciscan missionaries, so he invited Americans to populate
Texas. At first, the invitation was extended to 300 families; however, there was no official maximum set for the future.
Families were to be of good moral character, agree to abide by the laws of Mexico, and be Roman Catholic. In 1821, Stephen
F. Austin led the 300 families into Texas. In the years that followed, the American population in the Mexican province
exploded; by 1827, 12,000 Americans lived in Texas, outnumbering the Mexican population by 5,000.

Figure 14.1.1 : Stephen Fuller Austin | Portrait of Stephen Fuller Austin. Author: Flickr user “cliff1066” Source: Flickr license:
CC BY 2.0
In later years, the American population in Mexico grew even more. The American immigrants brought hundreds of slaves with
them, making Texas very different from the rest of turn-of-the-century Mexico; the institution of slavery had died out in the
late 1700s throughout much of Mexico, and slavery was no longer an economic foundation of the country. However, the
government seemed willing to make exceptions in order to attract immigrants to the state. Cheap land was one of the many
draws for Americans, slaveholding or no; immigrants to Texas paid 10 cents an acre for land. Comparable land was selling for
$1.25 an acre in the United States. Moreover, each male colonist was allowed to purchase 640 acres for himself and up to 320
additional acres for his wife, up to 160 acres for each of his children, and up to 80 acres for each slave that he brought into the
province. Finally, colonists were given a ten-year exemption from paying Mexican taxes.

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Figure 14.1.2 : Map of Mexican States and Territories in 1825 | Map of Mexican states and territories in 1825, showing
Coahuila y Texas. Author: Wikipedia User “Hpav7” Source: Wikimedia Commons
The Mexican government, believing that the Americans could be integrated into the Mexican community, passed a battery of
laws. All official transactions were to be in Spanish. Colonists were to settle deep into Texas; no foreigner was to settle within
60 miles of the U.S. boundary. Finally, foreigners who married Mexican citizens would be eligible for extra land. All of these
laws, the government believed, would facilitate the acculturation of Americans into Mexican society. However, all efforts
failed, and political, cultural, and economic tensions emerged between the Mexican government and the “Texans,” as opposed
to the Mexican “tejanos.” From a Mexican point of view, the Texans were a growing threat. Culturally, the Texans had
remained distinct from the Mexican population, due in great part to the fact that, although the colonists were required to be
Catholic in order to settle in Mexico, only a very small percentage of Texans professed Catholicism. Politically, Texans
dominated local government. The Mexican government also felt that the Texans were an economic threat to the tejanos. In one
instance, an American settler even threatened to illegally confiscate the land of any Mexican who could not produce a deed.
When the Mexican government moved to stop him, he led a revolt, which was ultimately unsuccessful. Slavery emerged as an
important issue of contention in Texas; the institution of slavery was tacitly illegal in Mexico, having been a part of the
revolutionary ideals, and limited by a series of restrictive laws. Though many of the Anglo immigrants were not slaveholders,
some slaveholding Texans circumvented this expectation by classifying their slaves as servants indentured for life. Although
the expansion of slavery into Texas had started small, the population had quickly grown and became a major source of
irritation and concern for the government. An 1829 government report confirmed that the colonization efforts were ultimately
unsuccessful because many Texans refused to be naturalized as Mexican citizens, remaining socially and culturally distinct and
isolated. The final straw, the report concluded, was the way in which the Texans ignored slavery laws.
The government sought to weaken the influence of the Texans in a variety of ways. In 1829, President Vicente Guerrero
officially outlawed slavery in Mexico; as slavery was not economically important anywhere in Mexico except for Texas, the
proclamation intended directly to weaken the position of the Texans. The government also encouraged Mexican immigration
into the state while simultaneously arresting further American immigration and strengthening the Texas garrisons. None of
these measures succeeded; indeed, they further incited the Texans and American expansionists, who called for the
incorporation of Texas into the United States through one means or another. In fact, many of the Texans had immigrated with
the firm idea that Texas would eventually become part of the United States. Two presidents had even offered to purchase Texas
from Mexico and were twice rejected.

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The United States was not the only foreign power with an eye to taking part of Mexico; in 1829, Spain invaded in an attempt
to retake the country as a colony. The invasion failed, and General Antonio López de Santa Anna Pérez de Lebrón (Santa Anna
for short) gained great popularity as the “hero of Tampico.” He helped to lead a coup against the Mexican president and was
himself elected president in 1833. The conservative Santa Anna overturned the Mexican Constitution of 1824, which was
based on the U.S. Constitution, in favor of a new, conservative constitution called the Siete Leyes (Seven Laws). The Siete
Leyes dissolved Congress and invested power in a centralized government backed by the military. This act was the last straw
for the Texans; the centralization of government was alien to the Americans, who were used to separation of powers, and
meant that Texans would have no political voice at all. They revolted, raising the “Federal Army of Texas” to defend the
Constitution of 1824 against Santa Anna and the centralists. Expansionists in the United States and Mexican liberals opposed
to Santa Anna alike encouraged the revolt. The revolt culminated in Texas’s declaration of independence on March 2, 1836
and the formation of the Republic of Texas, or the Lone Star Republic (1836-1846). Texas was not the only Mexican state to
declare independence; Santa Anna also faced rebellions in the Zacatecas and the Yucatán.

The Texas Revolution and the Lone Star Republic

Santa Anna successfully quelled the other rebellions but faced a greater challenge in Texas. In the winter of 1835, the president
himself led an army of 6,000 soldiers into Texas. He reached San Antonio in late February of 1836, roughly coinciding with
the Texans’ declaration of independence from Mexico. Santa Anna found that the Texans, including notables such as Davy
Crockett and Jim Bowie, had taken shelter in an old mission building known as the Alamo. The events that followed have been
presented in a variety of ways, most often reflecting the nationalist views of the historian. After holding the mission under
siege, on March 5 Santa Anna sounded the degüello, a bugle call used by the Spanish since the earliest days of colonization to
signal that the enemy was to be given no quarter; that is, they declared a battle to the death. Inside the mission, the Texans may
or may not have heard and understood the bugle call. The defenders’ understanding of the upcoming battle, nevertheless,
matched with Santa Anna’s as commander of the Alamo, W.B. Travis, declared there would be no surrender or retreat.
The following morning, the Mexicans began throwing wave after wave of troops against the wall; hundreds died under heavy
artillery fire from the Texans. After about an hour, however, the numerical superiority of the Mexican army prevailed, and they
breached the walls of the mission. The defenders suffered catastrophic casualties. Seven men survived the battle to surrender;
they were executed as prisoners. Thirty noncombatants inside the mission were spared, including several slaves of the Texans.
Santa Anna hoped thereby to convince other slaves to support the Mexicans in the rebellion. The high casualty rates on both
sides reinforced the idea that peaceable settlement was impossible. Another hard Texan defeat followed on the heels of the
Alamo. Again, Santa Anna ordered that all survivors taken as prisoners be executed, despite the protests of his commanding
general.
After the Alamo, Americans flocked from the United States to aid and avenge their Texan compatriots. In cities such as New
York and New Orleans, “Texas committees” organized volunteers to join the cause. Texans traveling to these cities gathered
even more volunteers with tales of the vast acreage of available land in Texas. Up until this time, several companies of tejanos
were active in the war effort and fought for independence. Indeed, largely ignored today is the fact that some of the defenders
at the Alamo were tejanos. But as more and more Americans came to join in the war effort, and as more and more evident the
anti-Mexican rhetoric within Texas became, most tejanos left the Texas Revolution.
Tejanos were not the only ones fleeing the Revolution; the costly defeats at Goliad and the Alamo resulted in an exodus of
civilians out of Texas to Louisiana, an exodus known as the Runaway Scrape. The Texas army under the leadership of Sam
Houston was also on the run from the larger army of Santa Anna. The Revolution finally came to an end at the Battle of San
Jacinto, where Houston pulled off a stunning and definitive victory when he took Santa Anna by surprise. The Texans forced
Santa Anna to sign not one, but two treaties: one public, one private. The public Treaty of Velasco declared the hostilities
between Mexico and Texas over but did not go so far as to recognize the Republic; the private Treaty of Velasco, however,
stated that in return for Santa Anna’s freedom, Mexico would accept the independence of the Lone Star Republic. After
returning to Mexico City, Santa Anna repudiated the private treaty, saying that he signed it under duress and as an individual
rather than dictator of Mexico. The “Texas problem” remained an issue for Mexico, although the nation was so racked with
internal problems that it never launched another full-scale invasion to retake Texas. The greatest point of dispute was the
border; Texas claimed the Rio Grande as the border, while Mexico held the Nueces River as the true boundary.
After the Revolution ended, Texas elected Sam Houston as its first president. The Lone Star Republic remained an
independent nation from 1836 to 1846. During these years, tens of thousands more American immigrants poured into Texas.

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Some, both in Texas and the United States (particularly expansionists in the slaveholding South), considered that the
annexation of the Republic to the Union was imminent; others took advantage of the plentiful land that the new government
was giving to heads of immigrant households. While the U.S. recognized Texas as an independent nation, some feared that this
annexation talk would inflame political tensions with Mexico. Indeed, the annexation of Texas and its boundary with Mexico
would later become a causal factor of the Mexican-American War.

14.2.2: Oregon
The second area of great expansion for the continental United States was the Oregon Territory, comprising present-day
Oregon, Washington, Idaho, and British Columbia, stretching from the 42nd parallel, the northernmost boundary of California,
to the 54th, the southernmost boundary of Alaska. Originally, Spain, Russia, Britain, and the United States all claimed the
Oregon Territory. Eventually, Spain and Russia dropped their claims, leaving Britain and the U.S. as remaining contenders.
British claims were based on prior discovery, exploration, and treaty rights; additionally, the most important colonizing agency
was the Hudson Bay Company, which engaged in active trade with the Indians of the Pacific Northwest. The U.S. claims were
also based on discovery, exploration, and treaty rights; additionally, a small number of Americans, including missionaries
trying to convert Pacific Northwest Indians, joined the claim of occupation to the American list. The two countries temporarily
resolved the matter with an 1818 agreement to a ten-year joint occupation, renewed in 1827, but the matter was far from
settled. In the period from 1816 through the 1840s, few Americans and Europeans settled in Oregon. But beginning in the
early 1840s, “Oregon Fever” gripped the United States. Oregon was touted as a land of pleasant climates and fertile soil.
Several thousand American settlers began a great westward migration over the Oregon Trail. By the mid-1840s, some 5,000
Americans had populated the Territory, thus strengthening the U.S. claim to Oregon. “Oregon Fever,” moreover, fueled the
idea of Manifest Destiny, popularizing it at the national level.

Figure 14.1.3 : The Oregon Trail | The route of the Oregon Trail is shown on a map of the western United States from
Independence, Missouri in the east to Oregon City, Oregon in the west. Author: Matthew Trump Source: Wikimedia Commons
license: CC BY SA 3.0
The famed Oregon Trail traveled by westward pioneers grew from rough trails cut by trappers, traders, and explorers. It ran for
about 2,000 miles from Independence, Missouri, across the western plains and the Rocky Mountains, ending in the valleys of
Oregon, most notably the Willamette Valley. As more and more immigrants came, other cities such as St. Joseph, Missouri,
and Council Bluffs, Iowa, vied for business as “jumping off points” onto the trail, as outfitting the westward-bound immigrants
was a profitable business in food and supplies, wagon repairs and fittings, and livestock. The journey over the trail was slow,
taking somewhere around five to six months to complete. Most people walked beside their wagons much of the way to reduce
the load on the oxen and wagon, and because the wagons were loaded to capacity with goods. The journey was dangerous;
accidents, including drowning during river crossings, were frequent. Diseases such as cholera and dysentery were the most
common killers on the journey. Although Hollywood later popularized the idea of pioneers “circling the wagons” against
Indian attack on the trail, such skirmishes were actually very rare and most often provoked by the immigrants themselves.
While thousands of immigrants died from disease and injury over the course of the 1840s, fewer than 120 were killed in
altercations with Indians. Cooperation and coordination was very important to the success of each group traveling the trail. For
this reason, many groups of immigrants drew up a formal document outlining the responsibilities and work assignments of

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each wagon in the group. The timing of the group’s departure and their daily progress was of pivotal importance as well; they
needed to be sure that they would reach the plains late enough to have adequate grazing for the livestock, but reach the western
mountains early enough to avoid the winter snows. As the movement into the west expanded, new routes branched off from
the original Oregon Trail. The California Trail extended the Oregon Trail south into California, the Mormon Trail into Utah,
and the Bozeman Trail north into Montana.

14.2.3: The Election of 1844

The issue of territorial expansion became one of the paramount issues of the election of 1844. Democrat James K. Polk,
Speaker of the House and protégé of Andrew Jackson, defeated Jackson’s old enemy Henry Clay in an election that revolved
largely around the issues of the possible annexation of Texas and acquiring some or all of Oregon. Polk, a more vocal
expansionist, won the election by a narrow majority. The Democrats also took both houses of Congress, causing many to read
the election as a mandate of expansionism.
Many Americans, Polk among them, set their sights on taking the Mexican provinces of New Mexico and California in
addition to Oregon. Polk hoped to obtain New Mexico and California peacefully but was prepared to use force to take them.
To this end, Polk settled with the British on the issue of Oregon in order to conserve American strength for obtaining further
territory from Mexico. The issue was further complicated by speculations and indications that Britain was considering signing
an alliance with Texas, which would forestall any hopes of annexation to the U.S.
Upon taking office, Polk therefore began talks with Britain. In the months after the election, the rhetoric over Oregon had
grown increasingly heated. Expansionists demanded that the United States take all of Oregon Territory, threatening war with
the slogan “Fifty-four forty or fight!” referring to the northernmost latitude of Oregon. Polk publicly embraced the demand for
“all of Oregon.” However, he was more than willing to accept a boundary line along the 49th parallel, splitting Oregon
between the U.S. and Britain. By accepting the 49th parallel boundary, the U.S. acquired Puget Sound, the first Pacific
deepwater port held by the U.S. Acquiring part of Oregon also brought territory that would become free states into the Union,
counterbalancing the possible annexation of Texas, sure to become slaveholding. By accepting less of Oregon, Polk and the
nation could prepare for the coming war with Mexico. This compromise displeased many of the more militant expansionists,
but others saw its pragmatism. Why “all of Texas” but not “all of Oregon”? Senator Thomas Hart Benton of Missouri
reportedly observed, “Because Great Britain is powerful, and Mexico is weak.”

14.2.4: The Mormon Trek

For one group, the Mormons, westward expansion was closely linked with religious beliefs. In a migration that paralleled the
early westward movement of the American population, Smith led his followers, the LatterDay Saints (or Mormons), from New
York to Ohio and then on to Missouri. In each place, they were met with skepticism and, often, hostility. NonMormons were
mistrustful of Mormon secret rituals, because the “new gospel” reopened the canon of the Bible, and because, led by Smith,
the group denied the authority of local governments. Non-Mormons also feared that the Mormon block voting would lead to
the creation of a local quasitheocracy. The Mormons were expelled from northwest Missouri in the 1838 Mormon War. They
came to settle in a town in Illinois that they renamed Nauvoo, where the Saints set to construct a temple and create their new
Zion. The city charter established independent courts and a Nauvoo militia. These institutions and a boom in local commerce
allowed the Mormons great autonomy in the region. During this period, Smith became increasingly powerful. He expelled
from the Church dissidents and many who spoke out against him. His practice of “plural marriage,” whereby he (and other
Mormon leaders) was husband to multiple wives, attracted the attention and outrage of many Americans. Smith’s growing
power in northwestern Missouri did not sit well with his Protestant neighbors, who feared that Mormons would come to
politically dominate the region. In 1844, these concerns led to the arrest of Joseph Smith. Smith and his brother were killed by
a mob as they were held for trial.
In the aftermath of Smith’s death, Brigham Young emerged as new church leader. Young oversaw the journey over the
Mormon Trail, a 1,300-mile journey westward from Nauvoo to the “promised land,” an area near the Great Salt Lake in Utah,
a sparsely-populated outlying province of Mexico. The first 12,000 Mormons made the trek in 1846-1847; more came later in
the period from 1848-1860. From 1856-1860, the church promoted the use of handcarts, rather than wagons pulled by draft
animals, as a more affordable means of migration. Many of these so-called “handcart pioneers” were new converts to the
church who had recently emigrated from Europe and now were on the last leg of their migration. Over the four-year period, ten
companies of handcarts made the journey along the trail; two of the ten had significant causalities.

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Soon after the 1847 trek, Mormons found themselves once again residents of the United States after the defeat of Mexico in
the Mexican-American War. The signing of the Treaty of Guadalupe Hidalgo ceded much of the modern-day American
Southwest, including Utah, to the United States. Utah was incorporated into a territory by Congress in 1860, and President
Millard Fillmore appointed Brigham Young territorial governor.

14.2.5: Before You Move On...

Key Concepts
Americans increasingly embraced the concept of Manifest Destiny in the 1840s. Manifest Destiny was associated not only
with land expansion, but also with the idea of Americanization of Indians and Mexican residents of areas such as Texas,
Oregon, and California. Moreover, many Americans likened the idea of the physical spread of the boundaries of the United
States with spreading freedom. The debate over expansionism was not a simple one, but raised complex questions about the
nature of freedom and republicanism and the role of the state in expansion. Many feared that expansionism was a threat to the
nation, whether in the form of overextension, national security, or a changing population. Private individuals engaged in
commercial and agrarian enterprises at the frontiers of expansion proved to be one of the greatest sources of pressure for
expansionism, as their economic activities often preceded national expansion into the territory.
The first major movement of Americans was into the Mexican province of Texas. Beginning in 1821, American settlers poured
into the region, with Americans soon outnumbering Mexicans. Cultural and religious differences and the American reliance on
slave labor led to rising tensions in Texas and, ultimately, to the Texas Revolution in 1835-1836. In 1836, Texas declared
independence as the Republic of Texas, or the Lone Star Republic.
In the early 1840s, thousands of Americans pushed westward into Oregon Territory over the Oregon Trail. The United States
and Great Britain both laid claim to Oregon Territory; however, the greater numbers of American settlers helped to bolster
U.S. claims to the region. In 1844, James K. Polk was elected president. Although he was an expansionist and courted the
American public with talk of taking “all of Oregon” for the United States, he negotiated with Great Britain to accept the 49th
parallel as the boundary between U.S. and British holdings. It should be noted that expansion into both Oregon and Texas
meant that the delicate balance between free and slaveholding states remained intact for the meantime. Finally, the Mormon
Trek was part of a greater movement in the westward expansion of the United States in the nineteenth century.
Test Yourself

Exercise 14.1.1
The concept of Manifest Destiny embraced the idea(s) that
a. the United States would expand “from sea to shining sea.”
b. residents of areas under expansion would be Americanized.
c. spreading the boundaries of the United States was equivalent to spreading freedom.
d. all of the above.

Answer
d

Exercise 14.1.2
American settlers in the Mexican province of Texas were typically unlike tejanos in that
a. many were slave owners.
b. they remained religiously distinct from the Roman Catholic tejanos.
c. they demanded popular sovereignty for all, including women.
d. A and B.
e. all of the above.

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 Answer
d

Exercise 14.1.3
“Fifty-four forty or fight!” refers to
a. the border dispute between the United States and Mexico: the U.S. claimed the Rio Grande as the border, Mexico
claimed the Nueces River.
b. American desires to expand to take “all of Oregon,” despite the British claims to the territory.
c. the struggles of the settlers as they traveled over the Oregon Trail.
d. the American desire to expand into California.

Answer
b

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14.2: The Mexican-American War
In the days after the election of 1844 before Polk’s inauguration, at the behest of lame duck President Tyler, Congress passed a
resolution to annex Texas. Although Mexico had finally recognized Texas’s independence in 1845, it held that the border
between Mexico and Texas was the Nueces River, as it had been from the colonial era. Texas—and now the United States—
held the border as the Rio Grande. The area between the two rivers was not the real point of contention for the two countries.
The Rio Grande wanders aimlessly for hundreds of miles far into New Mexico and presentday Colorado; in effect, claiming
the Rio Grande as the boundary tacitly laid claim to hundreds of thousands more acres. Mexico responded to annexation by
cutting off diplomatic relations with the U.S.; both countries prepared for war. As a last-ditch effort to avoid war, Polk sent
emissary John Slidell to Mexico City to resolve the border dispute. His secondary mission, however, was to secure California
and New Mexico for the United States. Slidell was authorized to pay $5 million for New Mexico and as much as $25 million
for Alta (Upper) California. Soon after Slidell’s arrival in Mexico City, the Mexican press learned of his mission to attempt
buying so much Mexican territory. Newspapers and journals denounced Slidell and the United States, and leaflets appeared all
over the city threatening rebellion if the government negotiated. Slidell was sent away.
Polk seized this opportunity to provoke war with Mexico. He ordered General Zachary Taylor into the disputed territory
between the rivers. When a skirmish broke out between Taylor and the Mexican general assigned to patrol the disputed
territory, Polk declared war, saying that he had tried every effort at reconciliation. “Mexico,” he stated, “has passed the
boundary of United States, invaded our territory, and shed American blood upon the American soil.” Despite opposition from
some Whigs, most notably Abraham Lincoln, Congress overwhelmingly approved the declaration of war. The view from
Mexico City was very different, however. Mexico contended that the United States had not only taken Texas, but also tried to
double Texas’s size. Moreover, when Mexico tried to defend its territory, the United States claimed that Mexico had invaded
U.S. land.
The U.S. strategy for the Mexican-American War called for a three-pronged attack on Mexico. The Army of the West was to
take and occupy New Mexico; the Army of the Center, to remain in northern Mexico. In anticipation of war with Mexico, the
United States assembled a Navy fleet off the coast of California, deploying Marines to the ships. In June of 1846, a small
group of mostly American settlers seized the garrison at Sonoma, California. The takeover was peaceable; in fact, no shots
were fired. Many of the settlers and californios, or Mexican residents of California, supported the rebellion, as the government
of the California territory was ineffectual and notoriously unstable: in the twenty-five year period before the revolt, leadership
had changed hands more than forty times. Upon taking the garrison, the rebels proclaimed a new government of the California
Republic. This Republic was very short-lived, lasting less than a month; indeed, few Californians knew of its existence.
Twenty-six days after the birth of the California Republic, an army corps of engineers under the command of John Frémont
marched into Sonoma. The Republic disbanded, and Frémont and the U.S. took over.
Meanwhile, the third prong of the U.S. attack on Mexico, the Army of Occupation, was to take Mexico City. General Winfield
Scott led an amphibious assault against the port city of Veracruz and, after taking the city, began his march to the capitol.
Scott’s arrival in Mexico coincided with great political turmoil in the nation; in the time since the outbreak of war, the Mexican
president had been overthrown by a general. The general then tried to abrogate the constitution, declare martial law, and take
power himself; consequently, he was overthrown in a rebellion. The army then invited Santa Anna back from exile to resume
the presidency. By the time that Scott took Veracruz, Santa Anna had only just arrived and taken command.

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 Figure 14.2.1 : Monument of the Boy Heroes | Monument to the boy heroes in Mexico City, Mexico. Author: Wikimedia User
“Thelma Matter” Source: Wikimedia Commons
Scott’s army was successful in taking much of the city. On August 20, Scott asked for surrender from Santa Anna; Santa Anna
agreed to negotiate. Rather than seriously negotiating surrender, however, Santa Anna used the time to shore up the city
defenses. By the time the armistice was at an end, Santa Anna was ready for battle, with his forces concentrated at
Chapultepec Castle at the center of the city. The defenders of the Castle, about 1,000 men and the cadets from the military
academy, laid land mines all over slopes of the steep hill upon which the Castle was located. The land mines failed to explode.
After a fierce battle, Scott’s forces prevailed. Mexican sources attest that by the time Scott’s forces reached the Castle, only a
handful of cadets remained to defend it. After the death of his comrades, the last remaining cadet wrapped himself in the
Mexican flag and jumped from the palace terrace, plummeting to his death on the steep rocks below.

14.3.1: The Treaty of Guadalupe Hidalgo and the Aftermath of the War
The Treaty of Guadalupe Hidalgo, which ended Mexican-American War, was signed in February of 1848. The treaty
confirmed the U.S. title to Texas and ceded the Alta California and New Mexico territories to the United States, some 525,000
square miles. Mexico was allowed to keep everything south of the Rio Grande. The United States agreed to pay $15 million
and to assume the claims of Americans against the Mexican government, about $3,250,000. In short, Mexico lost more than
half of its territorial landmass in the Treaty of Guadalupe Hidalgo. The land ceded to the United States eventually became the
states, or part of the states, of California, Arizona, New Mexico, Texas, Utah, Nevada, Colorado, Wyoming, and Kansas,
tremendously increasing the U.S. holdings and stoking the fires of Manifest Destiny. The most radical adherents of Manifest
Destiny had gone so far as to demand the annexation of not only “all of Texas,” but all of Mexico as well. Why, given the
expansionist climate of the era, did the United States not lay claim to all of Mexico? Perhaps the best answer to this question
lies in an examination of the problems that arose from the Mexican Cession itself.

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 Figure 14.2.2 : Mexican Cession | The Mexican Cession of the Treaty of Guadalupe Hidalgo, shown in white. The lands of the
Gadsden Purchase are shown in brown. Author: National Atlas of the United States Source: Wikimedia Commons
Through the Treaty of Guadalupe Hidalgo, the United States acquired about 55% of Mexico. Of course these lands were not
“empty” but (sparsely) populated with indigenous peoples and Mexican citizens who suddenly, and through no choice of their
own, found themselves residents of the United States. It is estimated that there were 80,000 Mexican citizens in California in
the late 1840s. Many of the families had been residents of the California or New Mexico territories for generations, since the
Spanish colonial period. Mexico was keenly interested in ensuring that these Mexicans would be provided for under the Treaty
of Guadalupe Hidalgo, which stated that all Mexican citizens who remained in the ceded lands for more than one year could
become naturalized U.S. citizens. Moreover, the original version of the treaty guaranteed that Mexican and Spanish land deeds
and grants would be recognized by the United States, allowing resident Mexicans to retain ownership of their lands. Later
amendments and interpretations of the treaty weakened this provision.
However, racial tensions emerged as the conquest of the territories of the Cession set a pattern for violence and racial
antagonism that still resonates today. Over the next decades, Mexicans and Mexican-Americans alike (some having become
citizens, some having declined the offer and remaining Mexican citizens) lost their lands as Texas, California, New Mexico,
and the United States government itself declared the Mexican and Spanish land deeds “imperfect,” questioned their veracity,
and ultimately took the lands of tejanos, californios, and others. Before the Treaty of Guadalupe Hidalgo, Mexicans owned all
lands valued over $10,000 in California; by the 1870s, they owned only one-quarter of these lands; by the 1880s, californios
were relatively landless. Thousands went from being landowners to laborers, sometimes on the very land they had once
owned. Much of the work was migratory in nature, and Mexican laborers were paid as much as two-thirds less than white
laborers. California, Texas, and other soon-to-be states also passed laws that targeted and politically unempowered Mexican-
Americans. A good example of this type of legislation was California’s Greaser Act, enacted in 1885. Technically, the Greaser
Act was an antivagrancy law. However, “vagrants” were defined in the law as “all persons who are commonly known as
‘Greasers,’ or the issue of Spanish and Indian blood…and who go armed and are not peaceable and quiet persons.” In general,
Hispanics became more and more alienated from the dominant society in the decades after Guadalupe Hidalgo.
So why didn’t the United States acquire “all of Mexico” after conquering Mexico City? Some historians argue that racism
played a large role. It was one thing to take the thinly-populated portions of Mexico that could be populated with many more
Caucasian Americans and another thing entirely to take over a country, or “uncontrolled dominion,” with a turbulent history,
populated with people of mixed ancestry, whom many Americans considered to be “mongrels.” Ultimately, Mexico would
have been an expensive, complicated problem for the United States. In taking the California and New Mexico territories, the
U.S. increased its land mass by some 20% and gained the important ports of San Diego and San Francisco, thus allowing for
trade with Asia, a much more pragmatic and manageable arrangement.
Because the Mexican Cession delineated by the Treaty of Guadalupe Hidalgo represented a tremendous increase to the land
mass of the United States, it did much to further manifest destiny. The last major territorial acquisition of the continental
United States followed on the heels of the Mexican Cession of 1848. In 1854, the United States and the Mexican government,

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once again under the control of the corrupt Santa Anna, signed the Mesilla Treaty, confirming the Gadsden Purchase. The
United States paid $10 million for Arizona’s Mesilla Valley, approximately 30,000 acres. The purchase also clarified and
finalized the border between the United States and Mexico. The U.S. desired this land for two additional reasons. First, the
Mesilla Valley offered the best terrain for building a transcontinental railroad along a deep southern route. Second, by securing
the land south of the Gila River, the United States finalized the border between California and Baja California (now the U.S.
and Mexico) as south of the San Diego Bay, offering an excellent harbor. Plans were made for building the trans-continental
railroad from Texas to San Diego, but nothing ever materialized.
The war was a tremendous military victory for the United States. The American military gained much experience. West Point
and the Naval Academy claimed that their training were the key to success and justified their existence with the war’s success.
The Marines won prestige as well and still sing of the conquest of “the halls of Montezuma.” The British and foreign skeptics
also reevaluated their opinion on American military strength in the war’s aftermath. However, the war was also costly. Some
13,000 Americans died, most from disease. The war’s monetary cost was about $100,000,000. The war also influenced foreign
relations in Latin America, especially with Mexico, in lasting ways. Mexico, and much of Latin America, considered that the
United States had deliberately provoked the war and that American greed was its primary underlying cause. The war
intensified what has been referred to as “Yankeephobia” in Latin America, leading to distrust and suspicion. The United States,
many contended, was untrustworthy, considered itself superior to others, and was a bully. It was called the “Colossus of the
North.” Perhaps most significantly, the war upset the carefully-maintained domestic political truce over slavery. Some felt that
the war would lead to a severe sectional crisis; poet Ralph Waldo Emerson observed, “Mexico will poison us!” Many Whigs
opposed the war on principle, believing that the U.S. had no legal right to the land south of the Nueces River, the original
boundary dispute between Texas and Mexico; many abolitionists believed that the war was provoked by the South in order to
expand slavery. The sheer amount of possible slaveholding territory coming into the Union upset the balance established by
the Missouri Compromise, reignited the slavery debate, and threatened stability. In response to this, Congressman David
Wilmot introduced a bill, called the Wilmot Proviso, which would have banned slavery in any territory acquired from Mexico
in the war. The measure was eventually defeated and never became law. However, it was strongly supported by representatives
of Congress from the free states. Ultimately, the Mexican War represented the looming question of slavery’s future.

Technological Development and Manifest Destiny

As the United States expanded geographically, it also underwent a period of growth and development in technology. Many
advocates of manifest destiny saw a clear link between territorial growth and technological development; internal
development, the mechanism that would spread American influence, followed on the heels of expansion. Two technologies
were particularly important in facilitating communication and travel across the great distances from coast to coast: the
telegraph and the railroad.
The development of a railroad infrastructure had begun in the 1830s in a limited area and proved to be viable and profitable.
Rail travel transformed the American economy in the 1840s and 1850s, linking port cities to the interior. Before the advent of
rail, the main route of commerce was along canal lines, which remained rail’s biggest competitor for quite some time.
Although the steam locomotive was faster, shipping costs were cheaper by canal. By the 1850s, however, the railroad network
had grown into the dominant means of transport by far. The growth of the telegraph and railroads also provided stability to the
growing nation. The United States had become so big that critics doubted its ability to effectively govern so much land and so
many people. Railroads and the telegraph provided one solution. Moreover, they facilitated the emergence of a national market
system.

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 Figure 14.2.3 : American Progress (1872) | John Gast painted American Progress in 1872. artist: John Gast Source: Library of
Congress
The expansion of railroads and the telegraph was not just an effect of manifest destiny. It was a continuation of an ongoing
discussion in the American government: the debate over internal improvements. The issue was first raised under Jefferson and
focused on the building of canals to better connect the trans-Appalachian frontier to the United States. The debate changed
with evolving technology and was raised again and again, most notably during the Madison and Jackson presidencies. A
constant in the debate was the discussion of whether or not it was appropriate to use federal money to fund these internal
improvements. Manifest destiny and its accompanying technological advances was simply the latest incarnation of this debate.
The significance of these technological advances to the concept of Manifest Destiny appears in various cultural artifacts. In
John Gast’s “American Progress” (1872), for example, the floating figure above the landscape resembles an angel and
symbolizes the American belief that Manifest Destiny was divinely ordained. How does the angel express the concept of
Manifest Destiny as espoused by John O’Sullivan? The paragraph below is from a nineteenth century description of the
painting by George Crofutt, who widely distributed his engraving of it.
In “American Progress,” a diaphanously and precariously-clad America floats westward through the air with the “Star of
Empire” on her forehead. She has left the cities of the east behind, and the wide Mississippi, and still her course is westward.
In her right hand she carries a school book— testimonial of the national enlightenment, while with her left she trails the
slender wires of the telegraph that will bind the nation. Fleeing her approach are Indians, buffalo, wild horses, bears, and other
game, disappearing into the storm and waves of the Pacific coast. They flee the ponderous vision— the star “is too much for
them.”
Technology enabled American expansionism throughout the North American continent by facilitating travel and
communication. Americans were not the only ones to harness this technological power towards an expansionist goal; during
the 1800s, these technologies further enabled European powers such as France, Britain, and Germany to establish a new kind
of colonialism: imperialism. The telegraph and railroad, along with other new technologies such as the steamboat and the
Maxim gun, one of the first machine guns, allowed a small number of Europeans to dominate large areas and great numbers of
people and fuel their own Industrial Revolutions. In this way, Manifest Destiny became a part of a greater nineteenth century
movement in expansionism.

14.3.2: Before You Move On...

Key Concepts

In 1845, the United States annexed Texas and admitted it to the Union. Tensions arose between the U.S. and Mexico over the
boundary; the U.S. claimed the Rio Grande as the border, with Mexico claiming the long-established boundary at the Nueces
River. The real reason for this border dispute was deeply linked to the expansionist desires of the United States; establishing
the Rio Grande as the border would lay claim to a substantial portion of Mexico outside of the confines of Texas. John
Slidell’s mission to Mexico exemplifies this intent; although his formal mission was diplomatic, he was secretly charged with
buying a substantial portion of the Mexican northwest for the United States. When Mexicans responded to this offer with
outrage, Polk took advantage by provoking war. The Mexican-American War, fought from 1846 to 1848, culminated with
General Winfield Scott’s invasion of Mexico City.
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The Treaty of Guadalupe Hidalgo ended the Mexican-American War. The treaty confirmed the U.S. title to Texas and ceded
the Alta California and New Mexico territories to the United States, some 525,000 square miles. Mexico lost more than half of
its territorial land mass. This ceded land eventually became all of, or part of, the U.S. states of California, Arizona, New
Mexico, Texas, Utah, Nevada, Colorado, Wyoming, and Kansas, tremendously increasing U.S. holdings and stoking the fires
of Manifest Destiny. In 1848, the Gadsden Purchase finalized the present border between the United States and Mexico with
the purchase of Arizona’s Mesilla Valley.
The incorporation of so much Mexican territory and so many Mexican citizens into the United States led to great problems.
The conquest of the territories of the Mexican Cession set a pattern for violence and racial antagonism that still resonates
today. Over the next decades, Mexicans and Mexican-Americans alike lost their lands in Texas, California, and New Mexico;
the United States government declared the Mexican and Spanish land deeds “imperfect,” questioning their veracity and
ultimately taking the lands of tejanos, californios, and others.
The Mexican-American War adversely and lastingly influenced foreign relations in Latin America. Mexico, and much of Latin
America, believed that the United States deliberately provoked the war, with American greed being its primary underlying
cause. The war intensified Latin American “Yankeephobia,” leading to distrust and suspicion. The war also upset the carefully-
maintained domestic political truce over slavery. Some felt that the war would lead to a severe sectional crisis. The sheer
amount of potential slaveholding territory coming into the Union upset the balance established by the Missouri Compromise,
reignited the slavery debate, and threatened stability.
Finally, the growth of technologies such as the telegraph and the railroad accompanied and enhanced the growth of Manifest
Destiny, connecting the burgeoning country in communication and ease of travel. Rail linked the ports and the interior,
facilitating trade and propelling the emergence of a national market system.
Test Yourself

Exercise 14.2.1

The “Greaser Act” is an example of

a. a law that targeted and politically unempowered Mexican-Americans.
b. “Yankeephobia” in Mexico.
c. an attempt to maintain the balance between free and slaveholding states in the aftermath of the Mexican-American War.
d. an attempt to settle territorial disputes between the United States and Mexico.

Answer
a

Exercise 14.2.2

The Wilmot Proviso is an example of

a. a law that targeted and politically unempowered Mexican-Americans.
b. “Yankeephobia” in Mexico.
c. an attempt to maintain the balance between free and slaveholding states in the aftermath of the Mexican-American War.
d. an attempt to settle territorial disputes between the United States and Mexico.

Answer
c

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Exercise 14.2.3

As a result of the Treaty of Guadalupe Hidalgo, Mexico lost more than half of its territorial land mass.
a. True
b. False

Answer
a

Exercise 14.2.4

The growth of rail and telegraph was hailed by expansionists as a means to

a. spread American influence.
b. enhance internal development.
c. facilitate trade.
d. all of the above.

Answer
d

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14.3: Conclusion
The era of expansionism in the United States gained great momentum in the 1840s and saw the finalization of the boundaries
of the continental United States. Manifest destiny justified expansion with a sense of mission and purpose. It portrayed
American expansion as inevitable, just, and divinely foreordained. Expansion added Texas and Oregon to the Union and was
an underlying cause of war with Mexico, which resulted in the acquisition of vast territories in the Southwest, including
California. Although it was a popular movement, it further antagonized the divisions between free and slaveholding states. As
the country grew and incorporated more and more territory, the delicate balance established by the Missouri Compromise
became increasingly tenuous. Finally, the era of Manifest Destiny profoundly influenced foreign relations, as some of the great
European powers such as Great Britain reevaluated their opinion of U.S. military strength, and Mexico and much of Latin
America came to regard the United States with increasing suspicion.

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14.4: Critical Thinking Exercises
Why did the United States eventually incorporate “all of Texas,” but not “all of Oregon” or “all of Mexico”? What factors
in the decision were similar, and which were different? What problems would the U.S. have faced if it had incorporated all
of these regions?
Using John Gast’s painting American Progress, explain how Americans viewed Manifest Destiny. Consider the role of
“progress” in technology, culture, and economy.

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14.5: Key Terms
Antonio López de Santa Anna
Stephen F. Austin
Battle of Goliad
Battle of the Alamo
John Frémont
Gadsden Purchase
Greaser Act
Vicente Guerrero
Manifest Destiny
Oregon Fever
James K. Polk
Republic of California
General Winfield Scott
John Slidell
General Zachary Taylor
Texas Republic
Texas Revolution
Treaty of Guadalupe Hidalgo
Mexican Cession

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14.6: Chronology
The following chronology is a list of important dates and events associated with this chapter.

Date Event
1821 Stephen F. Austin led the first 300 families into Texas

Mexican president Vicente Guerrero outlawed slavery in Mexico in an

1829 effort to weaken the influence of American settlers in the Mexican
province of Texas
1835-1836 Texas Revolution

1836 Formation of the Republic of Texas, or the Lone Star Republic

1840s “Oregon Fever”--expansion into Oregon Territory explodes

1844 James K. Polk elected President of United States

1846 Senator Thomas Hart Benson’s “Manifest Destiny” speech

1846-1848 Mexican-American War

1848 Treaty of Guadalupe Hidalgo

1854 Gadsden Purchase

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