San Diego County is located on the Pacific Ocean in the far southwest of the U.S. state of California along its border with Mexico. The county seat is the city of San Diego. San Diego County was one of the original counties of California, and was created in 1850 and named after San Diego Bay.
The county has a total area of 11,721 km², 93% of it is land and 7% of it is water. As of 2006, there were 2,941,454 people, 1,067,846 households, and 663,449 families residing in the county. The population density was 670/mi². North San Diego County is known locally as "North County".