The county was founded in 1883. It is named for Fall River which runs through it. Fall River County was established in 1883 and the county was then faced with deciding the location of the county seat. “Both towns voted - the living, those in the cemetery, and some besides,” said one old-timer, but Hot Springs won by sixteen votes. The courthouse construction contract was granted to Fred T. Evans. Local rumor has it that it was a deal made during a poker game. Evans held the land where the courthouse was ultimately built and he won the poker game. Architect Charles P. Brown was commissioned to draw up the proposal for the four-story sandstone block building. Work began in August 1891 at a cost of $23,000, with an addition of $3,750 for an “iron and steel jail.” Court was temporarily held in the Opera House. There was a great deal of controversy over this decision for the courthouse location, right down to who would pay for the flag to be placed outside. Several matters where ultimately heard by the Supreme Court, and the court took occupancy in 1892.
In addition to serving Fall River County, the court serves Oglala Lakota County which consists almost entirely of the Pine Ridge Indian Reservation. Matters related to the Oglala Sioux Tribal members, however, are handled by the Tribal Court in Pine Ridge.