Lancaster is the eighth-largest city in Los Angeles County, California and the 9th fastest growing city in the United States. Lancaster is located approximately 70 miles (112.5 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 an estimated 145,074 residents in 2009, and is the second-largest city on the California side of the Mojave Desert. As of the 2009 population estimate, the Palmdale / Lancaster, CA Urbanized Area (a US Census Bureau defined term) has a population of 476,845.