Agua Fria was originally a mining camp of the California Gold Rush, and was divided into Lower Agua Fria and Upper Agua Fria. Agua Fria means "cold water" in Spanish,[4] and the name was derived from two springs of cold water about a quarter mile below Lower Agua Fria (the main part of town). It may have been here that John C. Fremont's men discovered gold in 1849 on his Rancho Las Mariposas.
In 1850, it was a booming trade center and the final destination for many new arrivals in California. It was Mariposa County's first Seat of Justice from February 18, 1850, to November 10, 1851. A post office was established October 7, 1851.
John Charles "Charlie" Fremont moved the Mariposa County seat to Mariposa in 1854. The stately white Mariposa County Courthouse was built on present-day Bullion Street in 1854, and not only still stands, but is the oldest courthouse in California still in use as cases are still tried there to this day.
A post office operated at Agua Fria from 1851 to 1862.[3]
^ ab"Agua Fria". Office of Historic Preservation, California State Parks. Retrieved October 9, 2012.
^ abcDurham, David L. (1998). California's Geographic Names: A Gazetteer of Historic and Modern Names of the State. Clovis, Calif.: Word Dancer Press. p. 739. ISBN1-884995-14-4.