History of Hispanic and Latino Americans in the United States
In 1821, Mexico gained independence from Spain, annexing the southwest of the present United States, including Arizona. As missions began to wither, Mexico began auctioning off more land, causing the Pimería Alta and the Apachería to shrink as territory expanded. In the meantime, American mountain men began to enter the region, looking to trap beavers for their pelts. In 1836, Texas declared independence from Mexico and claimed much of the territory in the northern lands of Mexico. When the United States annexed Texas in 1846 over the strong objections of the Mexican government, U.S. troops moved into disputed territory. The hostilities erupted in the Mexican–American War (1846–1848). The U.S. occupied Mexico City and forced the newly founded Mexican Republic to give up its northern half, including the later Arizona.
Mexico City
The Grito de Dolores ("Cry of Dolores"), also known as El Grito de la Independencia ("Cry of Independence"), marked the beginning of the Mexican War of Independence. The Battle of Guanajuato, the first major engagement of the insurgency, occurred four days later. After a decade of war, Mexico's independence from Spain was effectively declared in the Declaration of Independence of the Mexican Empire on September 27, 1821. Unrest followed for the next several decades, as different factions fought for control of Mexico.