San Diego County, California

San Diego County
County of San Diego
Interactive map of San Diego County
Location in California
Coordinates: 33°01′N 116°46′W / 33.02°N 116.77°W / 33.02; -116.77
Country United States
State California
FormedFebruary 18, 1850
Named afterSaint Didacus of Alcalá
County seatSan Diego
Largest citySan Diego
Government
  TypeCouncil–CEO
  BodyBoard of Supervisors
  ChairVacant
  Vice ChairTerra Lawson-Remer (D)
  Chair Pro TemJoel Anderson (R)
  Board of Supervisors
Supervisors
  • Vacant District 1
  • Joel Anderson (R)
  • Terra Lawson-Remmer (D)
  • Monica Montgomery Steppe (D)
  • Jim Desmond (R)
  Chief Administrative OfficerEbony N. Shelton
Area
  Total
4,260.9 sq mi (11,036 km2)
  Land3,942 sq mi (10,210 km2)
  Water319 sq mi (830 km2)
Highest elevation
6,533 ft (1,991 m)
Population
  Total
3,298,634
  Estimate 
(2024)
3,298,799
  Density770/sq mi (300/km2)
GDP
  Total$257.341 billion (2022)
Time zoneUTC–8 (Pacific Time Zone)
  Summer (DST)UTC–7 (Pacific Daylight Time)
Area codes760/442 and 619/858
FIPS code06-073
Congressional districts48th, 49th, 50th, 51st, 52nd
Websitewww.sandiegocounty.gov

San Diego County (/ˌsæn diˈɡ/ ), officially the County of San Diego, is a county in the southwest corner of the U.S. state of California, north to its border with Mexico. As of the 2020 census, the population was 3,298,634; it is the second-most populous county in California and the fifth-most populous in the United States. Its county seat is San Diego, the second-most populous city in California and the eighth-most populous in the United States. It is the southwesternmost county in the 48 contiguous United States, and is a border county. It is home to 18 Indian reservations, the most of any county in the United States. There are 16 military installations of the U.S. Navy, Marine Corps, and Coast Guard in the county.

San Diego County comprises the San Diego–Chula Vista–Carlsbad, CA Metropolitan Statistical Area, which is the 17th most populous metropolitan statistical area and the 18th most populous primary statistical area in the United States. San Diego County is also part of the San Diego–Tijuana region, the largest metropolitan area shared between the United States and Mexico. From north to south, San Diego County extends from the southern borders of Orange and Riverside counties to the Mexico–U.S. border and the municipalities of Tijuana and Tecate in Baja California. From west to east, San Diego County stretches from the Pacific Ocean to its boundary with Imperial County, which separated from it in 1907.

San Diego County has more than 70 miles (113 km) of coastline. This forms the most densely populated region of the county, which has a mild Mediterranean to semiarid climate and extensive chaparral vegetation, similar to the rest of the western portion of Southern California. Precipitation and temperature extremes increase to the east, with mountains that receive frost and snow in the winter. These lushly forested mountains receive more rainfall than the average in Southern California, while the desert region of the county lies in a rain shadow to the east, which extends into the Desert Southwest region of North America.