Lancaster is a charter city located in northern Los Angeles County, situated in the Antelope Valley of the western Mojave Desert in Southern California. As of the 2020 census, Lancaster had a population of 173,516, making it the 158th-most populous city in the United States and the 31st most populous in California.
Lancaster functions as one of the two principal cities of the Antelope Valley region, alongside its southern neighbor Palmdale, with which it maintains a twin city relationship. The city's location in the high desert environment of the Mojave shapes its geography and climate.