Wikijunior:North America/United States/California
Arizona to the southeast, and to the south the Mexican state of Baja California. California is the most populous U.S. state. Its four largest cities are Los Angeles, San Diego, San Jose, and San Francisco. It is known for its varied climate and geography as well as its diverse population.
The area known as Alta California was colonized by the Spanish Empire beginning in the late 18th century. It and the rest of Mexico became an independent republic in 1821. In 1846 California broke away from Mexico, and after the Mexican-American War, Mexico gave California to the United States. California became the 31st state admitted to the United States on September 9, 1850.
California borders the Pacific Ocean, Oregon, Nevada, Arizona, and the Mexican state of Baja California. With an area of 160,000 square miles (414,000 km2) it is the third largest state in the United States in size, after Alaska and Texas.
In the middle of the state lies the California Central Valley, bounded by the coastal mountain ranges in the west, the Sierra Nevada to the east, the Cascade Range in the north and the Tehachapi Mountains in the south. The Central Valley is California's agricultural heartland and grows approximately one-third of the nation's food.
California is famous for earthquakes due to a number of fault lines present in the state, in particular the San Andreas Fault. It is vulnerable to tsunamis, floods, droughts, Santa Ana winds, wildfires, and landslides on steep terrain, and has several inactive volcanoes.