US Population Growth Mapped

The United States spans approximately 9.84 million square kilometers (3.8 million square miles) and is home to over 333 million people as of 2022. But this vast country wasn’t always settled as it is today. Going all the way back to before European contact, when the continent’s terrain was molded by thriving Indigenous cultures, is necessary to comprehend how we got here.

Population density map of what is now the United States (1492)

Long before 1776, before the colonies, before the map we know today, millions of Indigenous people lived across the lands that would become the U.S. Estimating their population isn’t easy, but archaeologists and historians have pieced together clues from burials, settlement patterns, and ecological footprints.

Approximations for North America’s population in 1492 range from 3.8 to 18 million people. Most Indigenous groups lived near rivers, lakes, and ocean coasts, where resources were abundant. The Mississippi River valley, the Pacific Northwest, and the Eastern Seaboard were particularly dense with vibrant communities.

Sadly, contact with European colonists brought epidemics like smallpox and measles—diseases to which Indigenous peoples had no immunity. These pandemics caused catastrophic population loss, far greater than losses from armed conflict. Some estimates suggest up to 90% of the population in some regions perished within a few generations of first contact.

Animated map of population density in the U.S. (1790 – 2010)

Jump forward three centuries, and we finally begin to get consistent census data. Starting in 1790, the U.S. government began counting people—mostly those in the original 13 states and their territories.

The animated map below visualizes U.S. population density by county from 1790 to 2010. It was created using Jonathan Schroeder’s county-level decadal estimates, with interpolated values for years between census counts. (The interpolation uses cubic splines of log-density—this means it assumes a smooth, consistent rate of change for each county.)

What’s fascinating here is watching the country “breathe”—early centers like Pennsylvania, New York, and Virginia initially hold the densest populations, but then you see waves of people pushing westward, clustering around new hubs like Chicago, Dallas, and Los Angeles.

When States Peaked: Shifting Population Power

Another way to think about population growth is to ask: When was each state at its population peak, relative to the rest of the country?

The next map below answers that exact question. You’ll notice that older Eastern states like New York, Pennsylvania, and Massachusetts reached their peak share of the total U.S. population earlier—often before 1900. But Western and Sunbelt states like Arizona, Nevada, and Florida only hit their peak recently, as people moved toward warmer climates and economic opportunities.

Westward Growth and Population Booms in the 20th Century

By 1890 the US had grown a lot and the eastern states were still very populated. But the west was expanding and new settlements were popping up all over the frontier. Here is the population density of the US in 6 degrees in 1890.

In the early 19th century, the U.S was in the midst of its Westward Expansion, which would greatly shape how population is distributed across the country. Following the Louisiana Purchase, and later with the Homestead Act of 1862, the federal government incentivized westward settlement by offering vast tracts of land at cheap prices, and promising new opportunities.

Settlers flocked in droves from the 1830s to the 1860s, lured by the prospect of new land, economic opportunities, and the potential for a new beginning. Whole cities and towns sprang up throughout the western frontier in mere decades. By 1917, California’s population was only 3.1 million. But by the turn of the century, its population had skyrocketed by a staggering 504% to 39.9 million in 2017.

As the United States marched into the 20th century, something changed dramatically in where people lived. Meanwhile, the East Coast continued to be a dense area of the country, while states including California, Texas and Florida gained major population centers — part of what’s known as Sunbelt migration.

The three most populous states, so far:

• California – 39.5 million
• Texas – 28.3 million
• Florida – 21 million

Such changes in population distribution were effected by forces including migration, job opportunities and the allure of warmer climes in the South and West. While the Westward Expansion was the impetus for initial settlement, the economic opportunities and way of life in these states continued to attract millions of people, creating the population centers seen today.

For most of American history, the eastern states were its most populous. But over the last century, the nation’s population has been distributed very differently. In 1917, California had only 3.1 million residents. That was after the population of California had grown 504% in 100 years to 39.9 million. According to 2024 data, the US’s three most populous states are California (39.5m), Texas (21m) and Florida (23m).

Animated map of population density in the U.S. (1990 – 2017)

As we saw earlier, the Westward Expansion was the basis for the development of California, Texas, and Florida. By the middle of the 20th century, with a wave of rapid urbanization in the United States, population giants such as New York, Chicago and Los Angeles emerged. This animated map illustrates population density from 1990 to 2022, making clear the regions where growth remained centralized and where suburban and exurban developments began to matter.

This migration into the suburbs has fueled expansion of metropolitan areas beyond the central core of cities, including Dallas-Fort Worth, Houston and Phoenix.

From the early days of westward migration to today’s growth of states like California, Texas and Florida, the population has changed dramatically. Knowing these shifts gives us insight into the past and helps us predict the future and what will drive it.

The population of the U.S. is a continuous story, influenced by economy, migration and the promise of new opportunities in different parts of the country. These changes give us a lot of information about the past, present and future – whether through maps or the stories that go with them.