Vista is a city in San Diego County, California. Vista is a medium-sized city within the San Diego-Carlsbad, CA Metropolitan Area. As of the 2020 Census, Vista had a population of 98,381. Current data estimates a 2023 population of 99,835. Vista's sphere of influence also includes portions of unincorporated San Diego County to the north and east, with a county island in the central west. Located just 7 mi (11 km) inland from the Pacific Ocean, it has a Mediterranean climate.

San Diego County, officially the County of San Diego, is a county in the southwestern corner of the U.S. state of California. 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. It is also home to 18 Native American tribal reservations, the most of any county in the United States.