Title: San Diego County, California
Content:  San Diego County, officially the County of San Diego, is a county in the southwestern corner of the state of California, in the United States. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county 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 city in the United States. It is the southwesternmost county in the 48 contiguous United States, and is a border 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 of the United States as of July 1, 
Title: San Diego, Texas
Content:  San Diego is a city in Duval and Jim Wells counties, Texas, United States. The population was 4,488 at the 2010 census. It is located primarily in Duval County, of which it is the county seat.
Title: San Diego County, California
Content:  According to the U.S. Census Bureau, the county has an area of 4526 sqmi, of which 4207 sqmi is land and 319 sqmi (7.0%) is water. The county is larger in area than the combined states of Rhode Island and Delaware. San Diego County has a varied topography. On its western side is more than 70. mi of coastline. Most of San Diego between the coast and the Laguna Mountains consists of hills, mesas, and small canyons. Snow-capped (in winter) mountains rise to the east, with the Sonoran Desert farther to the east. Cleveland National Forest is spread across the central portion of the county, while the Anza-Borrego Desert State Park occupies most of 
Title: San Diego County, California
Content:  Diego County was relatively large, and included all of southernmost California south and east of Los Angeles County. It included areas of what are now Inyo and San Bernardino Counties, as well as all of what are now Riverside and Imperial Counties. During the later part of the 19th century, there were numerous changes in the boundaries of San Diego County, when various areas were separated to make up the counties mentioned above. The most recent changes were the establishments of Riverside County in 1893 and Imperial County in 1907. Imperial County was also the last county to be established in California, and after this division, San Diego no longer extended from the Pacific Ocean to the Colorado River, and it no longer covered the entire border between California and Mexico.
Title: San Diego
Content:  San Diego is a city in the U.S. state of California on the coast of the Pacific Ocean and immediately adjacent to the Mexican border. With a 2020 population of 1,386,932, San Diego is the eighth most populous city in the United States and second most populous in California (after Los Angeles). The city is the county seat of San Diego County, the fifth most populous county in the United States, with 3,338,330 estimated residents as of 2019. The city is known for its mild year-round climate, natural deep-water harbor, extensive beaches and parks, long association with the United States Navy and Marine Corps, and recent emergence as a healthcare and biotechnology development center. 
Title: San Diego County, California
Content:  San Diego County is also part of the San Diego–Tijuana transborder metropolitan area, the largest metropolitan area shared between the United States and Mexico. San Diego County has more than 70. mi 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 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. 
Title: San Diego County, California
Content: Embarcadero (San Diego) 
Title: San Diego–Tijuana
Content:  Imperial Beach – 26,324 ; Lemon Grove – 25,320 ; Coronado – 24,697 ; La Joya – 22,126 ; Terrazas del Valle – 20,421 ; Villa del Campo – 13,906 ; Solana Beach – 12,867 ; Del Mar – 4,161 San Diego is located at 32.7°N, -117.15°W, just north of Tijuana. The city is divided into eight districts by the municipal government of the City of San Diego in accordance with policing and community service areas. The city lies south of North County, and west of East County, while also being north of parts of South Bay. Though the city boundaries grace Tijuana's, 
Title: Government of San Diego County, California
Content:  In the State Assembly, the 76th, 77th, 78th, 79th, and 80th districts are entirely within the county and parts of the 71st and 75th districts are within the county. In the State Senate, all of the 39th district and parts of the 36th, 38th and 40th districts are within the county. San Diego County is represented by the Third District in the State Board of Equalization. The San Diego Superior Court, which covers the entire county, is not a County department but a division of the State's trial court system. Historically, the courthouses were county-owned buildings that were maintained at county 
Title: San Diego County, California
Content:  Since at least 2014, San Diego County is the fifth most populous county in the United States. In 2000, only about 3% of San Diego County residents left the county for work while 40,000 people commuted into the metropolitan area.

Question: what county is san diego in?
Answer: San Diego County.