Los Angeles, often referred to by its initials L.A., is the largest city in California. With a 2020 population of 3,898,747, it is the second-largest city in the United States, following New York City. Los Angeles is known for its Mediterranean climate, ethnic and cultural diversity, Hollywood film industry and sprawling metropolitan area. The City of Los Angeles lies in a basin in Southern California, adjacent to the Pacific Ocean, and extends through the Santa Monica Mountains and into the San Fernando Valley, covering a total of about 469 square miles (1,210 km2). It is the seat of Los Angeles County, which is the most populous county in the United States with just over 10 million residents in 2020.