This starts at the Statue of Liberty. It's a retelling of America history starting with the Pilgrims. It is the spreading of settlers until they met the Indians. There is a lot of fighting until they agree to go west. Next, it's the War of Independence. Spreading west starts with The Louisiana Purchase and winning the war of 1812. The Monroe Doctrine lays claim to the whole hemisphere. There is no mention of divisive slavery with the Civil War. The Indians come back as the march west continues. Teddy runs up San Juan hill. WWI happens. There is peace and advancement until Pearl Harbor.
This is a patriotic propaganda short during war time. It skips over what can be skipped and explain away those that can't. It is effective for what it is. It is explaining what America stands for and fighting for in twenty minutes. There is no room for complications.