The jail facility in Mariposa County, like the county itself, has a long and rich history. The first recorded jail facility was built in 1852 from logs cut from surrounding forest, and was constructed close to the present day cemetery, near the creek behind the Trabucco Warehouse in the town of Mariposa. During this period, another tiny jail was built and used to detain prisoners prior to transportation to Mariposa in the town of Hornitos. This tiny facility is rich in local lore, and still stands in Hornitos. There was also a small local jail in the town of Coulterville, which is also still standing. In 1858 a fire destroyed most of the south end of Mariposa, including the jail there.
That same year, a replacement jail was constructed from 24” thick granite blocks quarried at Mormon Bar. This building still stands on Bullion Street. The new jail cost the county almost $15, 000, and was originally a two story structure with a flat roof and a gallows built on and extending from the east end of the building. In 1892 the building was gutted by fire, possibly set in an escape attempt, which took the life of the sole inmate. The jail was then rebuilt with the gable roof now seen on the building. This facility remained the Mariposa County jail until it was
condemned in 1963.
At that time the jail facility was incorporated at the current site of the Mariposa County Sheriffs Department, where it was slowly enlarged over time to meet the increasing need. The facility remained there until 1995. In that year, the Sheriff’s Department Dispatch organization took over the facility, and in March of that year the current jail was opened on Highway 49 North, approximately one mile north of the town of Mariposa.
Today the Mariposa County Adult Detention Facility, located at 5379 Highway 49 North, is a modern full function facility with a capacity of about 60 inmates.