In 1783 the United States reached from the Atlantic to the Mississippi. By 1853 it reached the Pacific. You have met each addition in this course; this lesson puts them side by side, with how each one came. The Mexican Cession and the Gadsden Purchase completed the main body of the country; Alaska and Hawaii came later.
Key idea
1783 Treaty of Paris lands (from Britain, by treaty). 1803 Louisiana (from France, purchase). 1819 Florida (from Spain, treaty). 1845 Texas (annexation). 1846 Oregon (from Britain, treaty). 1848 Mexican Cession (from Mexico, treaty after war). 1853 Gadsden Purchase (from Mexico, purchase). Later: 1867 Alaska (from Russia, purchase) and 1898 Hawaii (annexation).
Why it works
Why did the country grow in big pieces rather than mile by mile? Each piece was a claim recognized by another government: European empires, Mexico, or the Republic of Texas. Diplomats bargained over whole regions with rivers and lines of latitude as borders. The Gadsden Purchase, for example, bought a strip of land south of the Gila River because it was the best route for a southern railroad to California.
| Addition | Year | From | How |
|---|---|---|---|
| Louisiana | 1803 | France | Purchase, about \$15 million |
| Florida | 1819 | Spain | Treaty (Adams-Onís) |
| Texas | 1845 | Republic of Texas | Annexation |
| Oregon | 1846 | Britain | Treaty, 49th parallel |
| Mexican Cession | 1848 | Mexico | Treaty after war, \$15 million |
| Gadsden Purchase | 1853 | Mexico | Purchase, \$10 million |
| Alaska | 1867 | Russia | Purchase, \$7.2 million |
Worked example: Purchase, treaty or war?
A classmate says, "Most of the country was won by war." Test the claim against the list.
- Purchases: Louisiana, Gadsden, Alaska.
- Treaties without a war for that land: the 1783 lands (at the end of the Revolution), Florida, Oregon.
- Annexations: Texas, Hawaii.
- Treaty after a war fought partly over it: the Mexican Cession. So the claim is wrong for most additions, though the Mexican Cession was very large.
Answer: Most additions came by treaty or purchase; the Mexican Cession followed a war.
Common mistake
It is a mistake to think the country grew mostly by war with other countries. Most land came by treaty or purchase. But that is only half the story. Every one of these lands was already home to Native nations, and their land was taken through hundreds of treaties, many made under pressure, and through removals and wars. Check: for each region, ask both "which government gave it up?" and "whose homeland was it?"