Territorial Acquisitions

This is a United States territorial acquisitions and conquests list, beginning with American independence. Note that this list primarily concerns land the United States acquired from other nation-states; the territorial acquisitions from Native Americans are not listed here.

History of United States

1783–1853

The 1783 Treaty of Paris with Great Britain defined the original borders of the United States. There were ambiguities in the treaty regarding the exact border with Canada that led to disputes that were resolved by the Webster–Ashburton Treaty in 1842.

Louisiana

The Louisiana Purchase in 1803, was negotiated with Napoleon during the presidency of Thomas Jefferson; the territory was acquired from France for $15 million . A small

On December 29, 1845, Texas became the 28th state. Texas had claimed New Mexico east of the Rio Grande but had only made one unsuccessful attempt to occupy it; New Mexico was captured by the U.S. Army in August 1846 and then administered separately from Texas. Mexico acknowledged the loss of territory in the Treaty of Guadalupe Hidalgo of 1848.

Oregon Territory

Oregon Country, the territory of North America west of the Rockies to the Pacific, was jointly controlled by the U.S. and Britain following the Anglo-American Convention of 1818 until June 15, 1846 when the Oregon Treaty divided the territory at the 49th parallel . The San Juan Islands were claimed and jointly occupied by the U.S. and the U.K. from 1846–72 due to ambiguities in the treaty . Arbitration led to the sole U.S. possession of the San Juan Islands since 1872.

Mexican

Hawaii

In 1927 under the same 1905 Convention, the U.S. acquired two bancos from Mexico at the Colorado River border with Arizona. Farmers Banco, covering, a part of the Cocopah Indian Reservation at, was ceded to the U.S. with controversy. Fain Banco at also became U.S. soil.

Proposed: Based on aerial surveys in 2008, there are 138 cases where the widest channel of normal flow of the Rio Grande has shifted from previous surveys. Therefore, the International Boundary Line is to be changed under Article III of the 1970 Boundary Treaty. The result is 138 proposed transfers of territory that remain pending further evaluation and approval by the International Boundary and Water Commission and the two governments. Upon resolution, the U.S. is to cede 7 islands and 60 cuts in the Rio Grande to Mexico, totaling, while Mexico is to cede 3 islands and 68 cuts to the U.S., totaling .

Canada

In 1925, to correct an unintended effect from an earlier treaty, the U.S. ceded to Canada two enclaves comprising two and one-half acres of water territory in the Lake of the Woods.

Northern Mariana