In February 1879, the Northern Pacific Railroad laid track directly on the frozen Missouri River. Railcars carried construction materials to the relatively level lowlands on the west bank, where a new townsite was being platted under the direction of Northern Pacific division engineer Thomas Rosser. After completing the plat, Rosser used his business car as a real-estate office and sold lots to the public.
Mandan served as headquarters of the Missouri Division, which extended 200 miles from the Missouri River to the Yellowstone River at Glendive, Montana. A July 1879 contract with Smith & French for section houses and water tanks also called for a depot in Mandan. It was built south of Main Street at Stark Avenue, later renamed Collins Avenue.
Rosser designed Mandan's first depot in April 1879. The one-story, gable-roofed building measured 24 by 70 feet and had a 12-foot-wide platform on all sides.
In 1892, a flagpole from Fort Abraham Lincoln was installed in front of the building. After the Queen Anne depot opened three blocks west, the original depot was enlarged and used exclusively as a freight house.
The building was sold and moved in 1913 to make way for a four-story brick warehouse beside the main track. The Missouri Valley Grocery and Produce Company built the warehouse, which the John Iverson Company later purchased and a bank subsequently occupied.
The wooden depot was moved to the northeast corner of First Street and Third Avenue Northeast and converted into a duplex. When it was demolished around 1980, its bay window was salvaged and given to the State Historical Society, which reportedly placed it in storage.
