Southern California (colloquially known as SoCal; Spanish: Sur de California) is a geographic and cultural region that generally comprises the southernmost counties of California, and is the second-most populous urban agglomeration in the United States. The region contains ten 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 the Mojave Desert is located north on California’s Nevada border. Southern California’s southern border is part of the Mexico–United States border.