By 1873, Fort Clark had grown to regimental size, leading the U.S. Army Quartermaster Department to build six single-story infantry barracks and three two-story cavalry barracks. This one-story rectangular infantry barracks was built of coursed rubble limestone and featured a gable wood shingle roof, stone fireplaces, a central roof vent, and a shed front porch. Its open interior contained bunks for sixty-four soldiers and a single gun rack at the center of the open bay. The company barracks stood across the parade field from the officers’ quarters to the west. Today, this building is the best surviving example of its kind at Fort Clark and one of only a handful of Indian Wars period barracks remaining on any post in the nation.