When Did Mexico Become a Country? Not 1849.

Independence Achieved in 1821

Mexico became an independent country in 1821, after the Mexican War of Independence (1810–1821) against Spain.

Key Dates

• Sept 16, 1810: Grito de Dolores (Hidalgo's call to arms)
• Sept 27, 1821: Army of Three Guarantees enters Mexico City
• Sept 28, 1821: Declaration of Independence of the Mexican Empire

1849 Context

1849 was during the Mexican–American War aftermath (Treaty of Guadalupe Hidalgo, 1848), when Mexico ceded ~55% of its territory to the U.S. It was already a sovereign nation for 28 years.