Mexican Cession

The territory Mexico ceded to the United States under the 1848 Treaty of Guadalupe Hidalgo, encompassing much of the present-day American Southwest.

Mexican–American War: An armed conflict between Mexico and the United States from 1846 to 1848. The United States occupied the territory during this war, compelling Mexico to negotiate its transfer.
Compromise of 1850: A set of United States laws addressing slavery and territorial disputes after the Mexican–American War. Its provisions organized parts of the cession and tried to contain conflict over slavery.
Alta California: A Mexican province that covered much of present-day California and parts of neighboring states. It was among the largest regions transferred to the United States.
Texas: A state in the south-central United States that was an independent republic before joining the Union in 1845. Texas was annexed before the war and was not part of the territory ceded in 1848.
Treaty of Guadalupe Hidalgo: The 1848 treaty that ended the Mexican–American War and established a new boundary between Mexico and the United States. Its terms formally transferred the cession to the United States.
Wilmot Proviso: An 1846 proposal to prohibit slavery in territory acquired from Mexico. Its repeated failure exposed the sectional conflict triggered by acquiring the cession.
Santa Fe de Nuevo México: A Mexican province centered on present-day New Mexico and extending into nearby regions. Its territory formed another major part of the cession.
Republic of Texas: An independent state that existed from 1836 until its annexation by the United States in 1845. Its annexation preceded the cession and helped set the war’s disputed boundary.
Texas Annexation: The 1845 incorporation of the Republic of Texas into the United States. Annexation helped provoke the border dispute that led to war and the cession.
California Gold Rush: The mass migration to California after gold was discovered there in 1848. The rush rapidly populated a major part of the cession and accelerated California’s statehood bid.

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