Los Angeles County is the most populous county in the United States, with an estimated 9.7 million residents in 2025—more than 40 individual U.S. states—and is one of the most ethnically diverse areas in the country. Encompassing 88 incorporated cities and 101 unincorporated areas, its seat, the city of Los Angeles, is the second-most populous city in the U.S., and the county is globally famous as the birthplace of the American motion picture industry in the early 20th century. One of California's original counties created at statehood in 1850, it originally covered a vast territory that later split to form San Bernardino (1853), Kern (1866), and Orange (1889) counties. Geographically, it spans 4,083 square miles, featuring 70 miles of Pacific coastline, the Santa Monica and San Gabriel mountain ranges, and the western edge of the Mojave Desert. With its mix of urban centers, mountains, rivers, and desert, the county accommodates more than a quarter of all Californians.