American geographic and cultural region
Southern California is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area, the second most populous urban agglomeration in the United States. The region generally contains ten of California's 58 counties: Imperial, Kern, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, San Luis Obispo and Ventura counties. The Colorado Desert and the Colorado River are located on southern California's eastern border with Arizona, and San Bernardino County shares a border with Nevada to the northeast. Southern California's southern border with Baja California is part of the Mexico–United States border.