The main span is a pin-connected steel Pratt truss, about 129 feet (39 m) long, resting on concrete abutments and cylindrical piers.

On the south end, there are approach spans made of wood stringers (horizontal timbers) supported by timber pile bents; these replaced an original pony truss approach span.

[2] It was designed and built by William S. Hewett, a bridge builder based in Minneapolis, who was low bidder on the contract for the main bridge, at $4,500, and also for an approach span, at $750, which had to be added, perhaps because the original measurements or specifications were not adequate.

[2] The bridge carries Main Street road over Rock Creek, south of the town.

[2] Media related to Rock Creek Bridge (Joliet, Montana) at Wikimedia Commons