Flag of California	Seal of California

California is the most populous state of the United States. Located on the Pacific coast of North America, it is bordered by Oregon, Nevada, Arizona and Baja California in Mexico. The state's four largest cities are Los Angeles, San Diego, San Jose and San Francisco. California is known for its pleasant climate and ethnically diverse population. The state has 58 counties.

Inhabited by indigenous people for millennia, California was first colonized by the Spanish in 1769, and after Mexican independence in 1821, continued as part of Mexico. Following a brief period as the independent California Republic in 1846, California was annexed by the United States that same year, and was admitted to the Union as the thirty-first state on September 9, 1850.

California's diverse geography ranges from the sandy beaches of the Pacific to the rugged, snow-capped Sierra Nevada mountains in the east. The central portion of the state is dominated by the Central Valley, one of the most vital agricultural areas in the country. The Sierra Nevada contain Yosemite Valley, famous for its glacially-carved domes, and Sequoia National Park, home to the largest living organisms on Earth, the Giant Sequoia trees, and the highest point in the contiguous United States, Mount Whitney. The tallest living things on Earth, ancient Redwood trees, dot the Northern California coastline. California is also home to the lowest and hottest place in the Western Hemisphere, Death Valley. Bristlecone pines located in California's White Mountains are the oldest known trees in the world; one has an age of 4,700 years.

The California Gold Rush, beginning in 1848 dramatically changed California with an influx of population and an economic boom. The early part of the 20th century was marked by California's becoming the center of the entertainment industry, in addition to the beginning of growth of a large tourism sector. The Central Valley is home to California's important large agricultural industry. Other important industries have included the aerospace and oil industries. In recent decades, California has become a global leader in computers and information technology. If California were a country, its economy would rank among the ten largest of the world.

California adjoins the Pacific Ocean, Oregon, Nevada, Arizona, and the Mexican state of Baja California. With an area of 160,000 mi² (411,000 km²) it is the third largest state in the United States in size, after Alaska and Texas. If it were a country, California would be the 59th largest in the world, between Iraq and Paraguay.

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. Divided in two by the Sacramento-San Joaquin River Delta, the northern portion, the Sacramento Valley serves as the watershed of the Sacramento River, while the southern portion, the San Joaquin Valley is the watershed for the San Joaquin River; both areas derive their names from the rivers that transit them. With dredging, the Sacramento and the San Joaquin Rivers have remained sufficiently deep that several inland cities are seaports. The Sacramento-San Joaquin Bay Delta serves as a critical water supply hub for the state. Water is routed through an extensive network of canals and pumps out of the delta, that traverse nearly the length of the state, including the Central Valley Project, and the State Water Project. Water from the Sacramento-San Joaquin Bay Delta provides drinking water for nearly 23 million people, almost two-thirds of the state's population, and provides water to farmers on the west side of the San Joaquin Valley. The Channel Islands are located off the southern coast.

The Sierra Nevada (Spanish for "snowy range") include the highest peak in the contiguous forty-eight states, Mount Whitney, at 14,505 ft (4,421 m). The range embraces Yosemite Valley, famous for its glacially carved domes, and Sequoia National Park, home to the giant sequoia trees, the largest living organisms on Earth, and the deep freshwater lake, Lake Tahoe, the largest lake in the state by volume.

The state is home to Mount Whitney, the highest point in the contiguous United States, as well as the second lowest and hottest place in the Western Hemisphere, Death Valley.

To the east of the Sierra Nevada are Owens Valley and Mono Lake, an essential migratory bird habitat. In the western part of the state is Clear Lake, the largest freshwater lake by area entirely in California. Though Lake Tahoe is larger, it is divided by the California/Nevada border. The Sierra Nevada falls to Arctic temperatures in winter and has several dozen small glaciers, including Palisade Glacier, the southernmost glacier in the United States.

About 35% of the state's total surface area is covered by forests, and California's diversity of pine species is unmatched by any other state. California contains more forestland than any other state except Alaska. Many of the trees in the California White Mountains are the oldest in the world; one Bristlecone pine has an age of 4,700 years.

In the south is a large inland salt lake, the Salton Sea. Deserts in California make up about 25% of the total surface area. The south-central desert is called the Mojave; to the northeast of the Mojave lies Death Valley, which contains the lowest, hottest point in North America, Badwater Flat. The distance from the lowest point of Death Valley to the peak of Mount Whitney is less than 200 miles (322 km). Indeed, almost all of southeastern California is arid, hot desert, with routine extreme high temperatures during the summer.

Along the California coast are several major metropolitan areas, including Greater Los Angeles, the San Francisco Bay Area, and San Diego.

California is famous for earthquakes due to a number of faults, 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 volcanoes

Settled by successive waves of arrivals during the last 10,000 years, California was one of the most culturally and linguistically diverse areas in pre-Columbian North America; the area was inhabited by more than 70 distinct groups of Native Americans. Large, settled populations lived on the coast and hunted sea mammals, fished for salmon, and gathered shellfish, while groups in the interior hunted terrestrial game and gathered nuts, acorns, and berries. California groups also were diverse in their political organization with bands, tribes, villages, and on the resource-rich coasts, large chiefdoms, such as the Chumash, Pomo and Salinan. Trade, intermarriage, and military alliances fostered many social and economic relationships among the diverse groups.

The first European to explore the coast as far north as the Russian River was the Portuguese João Rodrigues Cabrilho, in 1542, sailing for the Spanish Empire. Some 37 years later, the English explorer Francis Drake also explored and claimed an undefined portion of the California coast in 1579. Spanish traders made unintended visits with the Manila Galleons on their return trips from the Philippines beginning in 1565. Sebastián Vizcaíno explored and mapped the coast of California in 1602 for New Spain.

Spanish missionaries began setting up twenty-one California Missions along the coast of what became known as Alta California (Upper California), together with small towns and presidios. The first mission in Alta California was established at San Diego in 1769. In 1821, the Mexican War of Independence gave Mexico (including California), independence from Spain; for the next twenty-five years, Alta California remained a remote northern province of the nation of Mexico. Cattle ranches, or ranchos, emerged as the dominant institutions of Mexican California. After Mexican independence from Spain, the chain of missions became the property of the Mexican government and were secularized by 1832. The ranchos developed under ownership by Californios (Spanish-speaking Californians) who had received land grants and traded cowhides and tallow with Boston merchants.

Beginning in the 1820s, trappers and settlers from the United States and Canada began to arrive in Northern California, harbingers of the great changes that would later sweep the Mexican territory. These new arrivals used the Siskiyou Trail, California Trail, Oregon Trail, and Old Spanish Trail to cross the rugged mountains and harsh deserts surrounding California. In this period, Imperial Russia explored the California coast and established a trading post at Fort Ross.