Broadus post office was established in 1900 and named after the Broaddus family. Powder River County was formed in 1919 when Frank Kelsey, a Moorhead rancher and Custer County state senator, introduced a bill drawn up by Helena attorney A.W. Heidel to create the county from the southern half of Custer County. In 1920 Broadus was named county seat, and Margaret Trautman donated 80 acres for the townsite. The town's streets were built wide enough for a horse-drawn carriage to turn around. In 1939 the Works Progress Administration expanded the courthouse. Winona Lewis Bryan, the first County Superintendent of Schools, recalled plodding through gumbo mud to the courthouse in wet weather, and I.D. Edwards remembered fetching cold drinking water from the well on the courthouse square for his grandmother in a little lard pail.