Central Mariposa County
5088 Bullion Street, Mariposa, CA 95338, United States
Built in 1854, the Mariposa County Courthouse is the oldest superior courthouse west of the Mississippi and the oldest courthouse in continuous use west of the Rockies. Mariposa County was formed in September 1850, even before California became the 31st State of the Union. Four years later the Mariposa County courthouse was built. The Court has conducted normal proceedings continuously in this courthouse ever since, the longest active period for any courthouse west of the Rocky Mountains.