what county is vacaville california in
Vacaville, California. Vacaville is a city located in Solano County in Northern California. The town is nearly halfway between Sacramento and San Francisco on I-80. It sits approximately 35 miles (56 km) from Sacramento, and 55 miles (89 km) from San Francisco. As of the 2010 census, Vacaville had a population of 92,428, making it the third largest city in Solano County.