Santa Clarita is a city in northwestern Los Angeles County in the U.S. state of California. With a 2020 census population of 228,673, it is the third-most populous city in Los Angeles County, the 17th-most populous in California, and the 103rd-most populous city in the United States. It is located about 30 miles northwest of downtown Los Angeles, and occupies 70.75 square miles of land in the Santa Clarita Valley, along the Santa Clara River.