History

California officially became a U.S. state on September 9, 1850. This marked a significant moment in American history, following the Mexican-American War and the Treaty of Guadalupe Hidalgo in 1848, where Mexico ceded California and other territories to the United States.

The treaty that ended the Mexican-American War and ceded California to the United States was the Treaty of Guadalupe Hidalgo, signed on February 2, 1848. This treaty marked the conclusion of the war between the U.S. and Mexico, which had been fought from 1846 to 1848 over territorial disputes, particularly in Texas and the lands that are now the southwestern United States.