After the first thirteen states, the country grew in big pieces. The 1783 peace treaty with Britain set the western border at the Mississippi River. After that, land was added in several large steps.
Key idea
The big additions: the Louisiana Purchase (1803, from France), Florida (1819 treaty with Spain), Texas (1845, annexed), the Oregon Country (1846, divided with Britain), the Mexican Cession (1848, from Mexico after the U.S.-Mexican War), the Gadsden Purchase (1853, from Mexico), Alaska (1867, from Russia) and Hawaii (1898, annexed).
Why it works
Why in big pieces? Each piece came from a single agreement with whoever held the land: a purchase from France or Russia, a treaty with Spain or Britain, Texas and Hawaii agreeing to join, or the treaty that ended a war with Mexico. One agreement could move a border hundreds of miles. American Indian nations already lived on all of these lands, and their own treaties with the United States are another part of this history.
Worked example: In order
Put these in order: Alaska, the Louisiana Purchase, the Mexican Cession.
- Louisiana Purchase: 1803.
- Mexican Cession: 1848.
- Alaska: 1867.
Answer: Louisiana Purchase, Mexican Cession, Alaska.
Common mistake
People picture the country growing west one thin strip at a time. It grew in big pieces, by purchases, treaties, annexations and a war, and not always from east to west. The Louisiana Purchase reached the Rocky Mountains in 1803, and Alaska was added in 1867, more than twenty years before Washington, Montana or the Dakotas became states.