Prominent landowner and state senator Edward Donlan won a political victory in the 1906 legislature with the designation of Thompson Falls as county seat for Sanders County over the rival town of Plains. By compromise, most county posts were filled by 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. It is Thompson Falls’ oldest surviving county building. The structure 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 the four cells, each designed to hold four individuals. One cell, separated from the others, was for women and children detainees. Steel bars fastened by beams to a concrete floor and cement ceiling assured strict security within 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 and is a fine example of a combination jail/sheriff’s residence of the period.