Vacaville is a city located in Solano County, California. Sitting about 35 miles from Sacramento and 55 miles from San Francisco, it is on the edge of the Sacramento Valley in Northern California. The city was founded in 1851 and is named after Juan Manuel Vaca. As of the 2020 census, Vacaville had a population of 102,386, making it the third-largest city in Solano County. Other nearby cities include Fairfield, Suisun City, Dixon, Rio Vista, Vallejo, Benicia, and Napa.