Prominent landowner and state senator Edward Donlan secured the designation of Thompson Falls as county seat for Sanders County in the 1906 legislature over the rival town of Plains. By compromise, most county posts went to Plains appointees, but Donlan donated his own land for the new county courthouse and jail. The two-story Italianate style jail was built in 1907 by contractors Christian and Gobelet at a cost of $5,000, and it is Thompson Falls’ oldest surviving county building. It was originally divided into incarceration cells on the second level and living quarters for the sheriff and his family on the first, with separate entrances for each level. The Paully Jail Company of St. Louis installed four cells, each designed to hold four individuals, including one cell separated from the others for women and children detainees. Steel bars fastened by beams to a concrete floor and cement ceiling secured the cell room, while an eighteen-inch solid brick wall with steel door and locks isolated it from the stairway entrance. Though steel bars have been recently added to the downstairs windows, the building retains its 1907 appearance as a fine example of a combination jail and sheriff’s residence of the period.