Santa Clarita is the third-largest city in Los Angeles County, and the 23rd largest in the state of California. As of the 2010 census it had a population of 176,320, and in 2018 the population was estimated to be 210,089. The city has gained much of this rapid population increase by annexing numerous unincorporated areas. It is located about 30 mi northwest of downtown Los Angeles, and occupies most of the Santa Clarita Valley in northwestern Los Angeles County. It is a notable example of a U.S. edge city or boomburb.