This is one of the rarer items on display among the outdoor displays at the museum. It is a belly dump ore wagon, designed to be driven over an ore hopper then its load of ore dumped by opening the doors which comprise the bottom of the wagon. Gravity does the work of opening the doors, then a chain and ratchet mechanism is used to close the doors. Depending on the steepness of the terrain, the wagon would be pulled by either one or two teams of horses.
In the area there was quite a bit of gold mining taking place, beginning as early as 1850, and this wagon would not be much newer than that. The hopper into which the ore was dumped would have been part of either an ore concentrator or the equipment used to load ore onto railway cars for shipment.
If you're passing through Deer Lodge, be sure to check out
All The Museums. There are six here within a block, three in the old Montana State Prison and three across the street from it.