Historical Territories Once Part of Mexico

Following independence from Spain in 1821, Mexico's territory extended far beyond its current borders. Over the subsequent decades, Mexico ceded or lost vast regions through treaties, wars, and annexations. The following areas were once part of Mexican territory:

Present-Day U.S. States (1821–1848)

• Texas (1821–1836, independent republic until U.S. annexation)
• New Mexico
• Arizona
• California
• Nevada
• Utah
• Colorado
• Wyoming
• Montana
• Idaho
• Oregon (1821–1846)
• Washington (1821–1846)
• Alaska (1821–1867, sold by Russia to U.S.)

Central American Nations (1821–1838/39)

• Belize (1821–1836)
• Guatemala (1821–1838)
• El Salvador (1821–1839)
• Honduras (1821–1838)
• Nicaragua (1821–1838)
• Costa Rica (1821–1838)

These territories were lost primarily through the Mexican–American War (1846–1848), the Treaty of Guadalupe Hidalgo, the Gadsden Purchase, and the dissolution of the Federal Republic of Central America. Note that while the prompt refers to "countries," most listed are now U.S. states; only the Central American nations became independent countries.