San Diego is a coastal Southern California city located in the southwestern corner of the continental United States. As of 2005, the city has a population of 1.2 million. It is the second-largest city in California and the eighth-largest in the United States.[1] It is the county seat of San Diego County.GR6 and is the economic center of the San Diego–Carlsbad–San Marcos metropolitan area, the 17th-largest metro area in the U.S. with a population of 2.9 million as of 2006, and the 21st largest Metropolitan area in the Americas when including Tijuana (See:San Diego-Tijuana Metro.).