Four Countries That Ceded Territory Now in the United States

1. Great Britain

Treaty of Paris (1783) — Ended Revolutionary War. Ceded 13 colonies + territory to Mississippi River. (Florida returned to Spain separately.)

2. France

Louisiana Purchase (1803) — $15M. 828,000 mi² (Mississippi River to Rockies, Gulf to Canada). Doubled US.

3. Spain

Adams-Onís Treaty (1819) — Ceded East & West Florida. Defined US boundary to Pacific (ceded Oregon Country claims).

4. Mexico

Treaty of Guadalupe Hidalgo (1848) — Ended Mexican War. $15M + assumed claims. Ceded CA, NV, UT, AZ, NM, CO, WY (Mexican Cession).
Gadsden Purchase (1853) — $10M. Southern AZ/NM strip for railroad.

Others (Partial / Later)

• Russia: Alaska Purchase (1867) — $7.2M
• Hawaii (Kingdom/Republic): Annexation (1898)
• Spain (again): Spanish-American War (1898) — Puerto Rico, Guam, Philippines

The four above (Britain, France, Spain, Mexico) transferred the vast majority of the contiguous 48 states.