California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area (after Alaska and Texas). It is home to the nation's second- and sixth-largest census statistical areas (Los Angeles Metropolitan Area and San Francisco Bay Area), and eight of the nation's 50 most populous cities (Los Angeles, San Diego, San Jose, San Francisco, Fresno, Sacramento, Long Beach and Oakland). The capital city is Sacramento.
California's diverse geography ranges from the Pacific Coast at the west side, to the Sierra Nevada mountains in the east—from the Redwood–Douglas-fir forests of the northwest, to the Mojave Desert areas in the southeast. The center of the state is dominated by Central Valley, a major agricultural area. California contains both the highest and lowest points in the contiguous United States (Mount Whitney and Death Valley), and has the third-longest coastline of all states (after Alaska and Florida). Earthquakes are a common occurrence due to the state's location along the Pacific Ring of Fire: about 37,000 are recorded annually.
The name California once referred to a large area of North America claimed by Spain that included much of modern-day Southwestern United States and the Baja California peninsula. Beginning in the late 18th century, the area known as Alta California, comprising the California territory north of the Baja Peninsula, was colonized by the Spanish Empire as part of New Spain. In 1821, Alta California became a part of Mexico following its successful war for independence. Shortly after the beginning of the Mexican-American War in 1846, a group of American settlers in Sonoma declared an independent California Republic in Alta California. Though its existence was short-lived, its flag became the precursor for California's current state flag. American victory in the war led to the Treaty of Guadalupe Hidalgo, in which Mexico ceded Alta California to the United States. Western areas of Alta California became the state of California, which was admitted as the 31st state on September 9, 1850.
The California Gold Rush beginning in 1848 led to dramatic social and demographic change, with large scale immigration from the U.S. and abroad and an accompanying economic boom. Key developments in the early 20th century included the emergence of Los Angeles as the center of the American entertainment industry, and the growth of a large, state-wide tourism sector. The late 20th century saw the development of the technology and information sectors, punctuated by the growth of Silicon Valley. In addition to California's prosperous agricultural industry, other important contributors to its economy include aerospace, education, and manufacturing. If California were a country, it would be the eighth-largest economy in the world and the 35th most populous nation.