Santa Clarita, officially the City of Santa Clarita, is the third largest city in Los Angeles County, California, United States and the eighteenth largest in the state of California. The city has annexed a number of unincorporated areas, contributing to the large population increase. It is located about 35 miles (56 km) northwest of downtown Los Angeles, and occupies most of the Santa Clarita Valley. It is a notable example of a U.S. edge city or boomburb.