Lancaster is a charter city in northern Los Angeles County, in the Antelope Valley of the western Mojave Desert in Southern California. As of the 2010 census it had a population of 156,633, and in 2018 the population was estimated at 159,053, making Lancaster the 33rd largest city in California. Lancaster is part of a twin city complex with its southern neighbor Palmdale, and together they are the principal cities within the Antelope Valley region.