San Diego is located in the southwestern corner of the continental U.S. In 2005, the city had a population of 1,256,951. The city is the second largest city in California and the 8th largest city in the United States. The City of San Diego is the county seat of San Diego County. The metropolitan area of San Diego, Carlsbad and San Marcos is the 17th largest metro area in the US. The metro area has a population of 2.9 million as of 2006. The 21st largest metropolitan area includes the Tijuana and San Diego area.

The city lies just north of the Mexican border and shares a border with Tijuana. The county lies just south of Orange County and is home to miles of beaches with a Mediterranean climate. The city includes the 16 military facilities including bases for the United States Navy, United States Coast Guard and the United States Marine Corps.