In 1848, the Treaty of Guadalupe Hidalgo was signed, marking the end of the Mexican-American War. Under the terms of the treaty, Mexico ceded Alta California and New Mexico to the United States. This cession included current Arizona and New Mexico, as well as parts of Utah, Nevada, and Colorado (Article V). Additionally, Mexico waived all claims to Texas and recognized the Rio Grande as the southern boundary with the United States (Article V).Before this cession, California was home to a native population that had been reduced to less than 100,000 people.
Additionally, there were 14,000 permanent residents in the area. The Spanish government had established Catholic missions in California in order to spread their faith in the New World. These missions gave rise to many cities and towns that are still present today. The Mexican Cession resulted in 55 percent of Mexico's territory being ceded to the United States. This included the current states of California, Nevada, Utah, New Mexico, most of Arizona and Colorado, and parts of Oklahoma, Kansas and Wyoming.
Californians were allowed to trade with foreigners and foreigners could own land in the province once they had naturalized and converted to Catholicism. The Bear Flag Revolt was an insurrection that divided California from Mexico. This revolt was one of the first aggressive actions taken by non-Mexicans who had moved into Northern California from Oregon. During this time period, many cities were established and named including San Diego, Los Angeles, and San Francisco. Ranch life flourished in California during this time period and American trappers began to enter the territory. Father Junipero Serra was a Franciscan father who had a tremendous influence on the colonization of California through his establishment of 21 Spanish missions along the coast.
The first organized group of settlers from the United States to cross the plains into California was led by John Bidwell and John Bartleson in 1841. In 1821, Mexico achieved independence and news of this event reached Alta California the following year. Californians were now allowed to trade with foreigners and foreigners could own land in the province once they had naturalized and converted to Catholicism. California's vast natural resources and thriving population led to its desire to become a part of the United States as a state. On March 10th 1848, the Senate approved a treaty that led California and much of the Southwest to join the United States. Many people today are unaware that states like Texas, Arizona, and California were once part of Mexico.
