Vacaville, California is located in Solano County, California, United States, between Sacramento and San Francisco. As of the 2000 census, the city had a total population of 88,625. According to the Community Development Department of the City of Vacaville, the total population as of 2005 was 96,735. The city was founded in 1852 by William McDaniel and named after Juan Manuel Vaca, who had received a substantial land grant from Don Mariano Guadalupe Vallejo.