1.1: Introduction to the State
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2 million residents, as of 2024, across a total area of approximately 163,696 square miles (423,970 km2), it is the most populous U.S. state and the 3 rd largest by area. 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. 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. San Francisco is the second most densely, (which is a calculation of how many people per square mile or kilometer) populated major city in the country. Los Angeles County is the country's most populous, while San Bernardino County is the largest county by area in the country. California borders Oregon to the north, Nevada and Arizona to the east, the Mexican state of Baja California to the south; and has a coastline along the Pacific Ocean to the west.
The economy of the state of California is the largest in the United States, with a $3.4 trillion gross state product (GSP) as of 2022. It is the largest sub-national economy in the world. If California were a sovereign nation, it would rank as the world's fifth-largest economy as of 2022.
Prior to European colonization, California was one of the most linguistically diverse areas in pre-Columbian North America and contained the highest Native American population density north of what is now Mexico. European exploration in the 16 th and 17 th centuries led to the colonization of California by the Spanish Empire. In 1804, it was included in Alta California province within the Viceroyalty of New Spain. 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. The California Gold Rush started in 1848, only 9 days after Mexico signed over the greater part of California in the Treaty of Guadalupe, which led to dramatic social and demographic changes, including large-scale immigration into California, a worldwide economic boom, and the California genocide of indigenous people. The western portion of Alta California was then organized and admitted as the 31 st state on September 9 th , following the Compromise of 1850.
The state's extremely diverse physical geography ranges from the Pacific Coast and metropolitan areas in the west to the Sierra Nevada mountains in the east, and from the redwood and Douglas fir forests in the northwest to the Mojave Desert in the southeast. The Central (or often referred to as the Great) Valley, a major agricultural area, dominates the state's center. California is well known for its warm Mediterranean climate and monsoon seasonal weather. The large size of the state results in climates that vary from moist temperate rainforest in the north to arid desert in the interior, as well as snowy alpine in the mountains.
California is home to the world’s oldest, tallest, and largest trees—it also has the highest and lowest point in the lower 48 states. The geography and geology provide tourists the opportunity to go skiing and surfing in the same day, while driving by some of the tallest and lowest elevations on the continent. No other location has the cultural and spatial diversity, grandeur, and geological variety than California. The best way to understand what California ‘is’, would be to start with the story of the Isle of California.