California: Americanization

For the United States, Mexico’s independence in 1821 meant the beginning of overland travel to the Pacific: American trappers and traders traversed the Rocky Mountains and visited California. Trade between California and the United States began in the 1840s. Although there were only a few hundred Americans living in California at the time, they controlled the trade. When war erupted between Mexico and the United States in 1846, American soldiers supported by local Mexicans quickly seized California from Mexican authorities.