Lancaster is the fourth-largest city in Los Angeles County, California, and the ninth-fastest growing city in the United States. Lancaster is the principal city within the Antelope Valley. Lancaster is located approximately 70 miles (110 km) north (by road travel) of the city of Los Angeles in Southern California's Antelope Valley. It is separated from the Los Angeles Basin by the San Gabriel Mountain Range to the south and from Bakersfield and the San Joaquin Valley by the Tehachapi Mountain Range to the north. The population of Lancaster has grown from 37,000 residents at the time of incorporation in 1977, to 156,633 people as of the end of 2009/2010 which makes it the largest city on the California side of the Mojave Desert.