The area became a part of Mexico in 1821, following its successful war for independence, but was ceded to the United States in 1848 after the Mexican–American War.
In 1804, it was included in Alta California province within the Viceroyalty of New Spain. European exploration in the 16th and 17th centuries led to the colonization of California by the Spanish Empire. Prior to European colonization, California was one of the most culturally and linguistically diverse areas in pre-Columbian North America and contained the highest Native American population density north of what is now Mexico. The San Francisco Bay Area Combined Statistical Area had the nation's highest gross domestic product per capita ($106,757) among large primary statistical areas in 2018, and is home to five of the world's ten largest companies by market capitalization and four of the world's ten richest people. The Greater Los Angeles area and the San Francisco Bay Area are the nation's second- and third-largest urban economies ($1.0 trillion and $0.5 trillion respectively as of 2020 ), after the New York metropolitan area ($1.8 trillion). If it were a country, it would be the 37th most populous country and the fifth largest economy as of 2020. The economy of California, with a gross state product of $3.2 trillion as of 2019, is the largest sub-national economy in the world. San Francisco, which is both a city and a county, is the second most densely populated major city in the country (after New York City) and the fifth most densely populated county in the country, behind four of New York City's five boroughs. Los Angeles County is the country's most populous, while San Bernardino County is the largest county by area in the country. Sacramento is the state's capital, while Los Angeles is the most populous city in the state and the second most populous city in the country (after New York City). The Greater Los Angeles area and the San Francisco Bay Area are the nation's second and fifth most populous urban regions respectively, with the former having more than 18.7 million residents and the latter having over 9.6 million. It is also the most populated subnational entity in North America and the 34th most populous in the world. With over 39.5 million residents across a total area of approximately 163,696 square miles (423,970 km 2), it is the most populous and the third-largest U.S.
It shares a border with Oregon to the north, Nevada and Arizona to the east, and the Mexican state of Baja California to the south. California is a state in the Western United States.