Over the next 20 years, the Indian situation was cleared up, and the railroads were on the move again. The Milwaukee Road started building west of Chamberlain towards Rapid City on March 1, 1906. A floating pontoon bridge was built at Chamberlain to cross the Missouri River. This pontoon bridge approaches had fixed pilings and decks, and then a hinge mechanism to allow the channel deck sections to move up and down with the pontoon boats. The deck would split in the middle and the two sections could be towed towards each shore to make an opening for navigation traffic. The bridge was left open like this in the winter to prevent ice damage. Trains were restricted to 5 miles per hour when crossing the pontoon bridge.
The pontoon bridge was replaced by a steel bridge in 1923. The building of the Fort Randall Dam would cause the steel bridge to be flooded out when Lake Francis Case filled. Thus, in 1953, the steel bridge was removed and the current bridge was built by the US Army Corps of Engineers. The new bridge features two large through truss sections, and a long string of deck truss sections. The Chamberlain Railroad Bridge was the longest bridge on the Milwaukee Road system at a length of seven-eighths of a mile.
The Milwaukee Road hit hard times with the overall railroad slowdown in the late 1970s, and found itself bankrupt several times in the late 1970s. A restructured version of the railroad failed again, so it was forced to merge with the Soo Line Railroad in 1985. Prior to that merger, the Milwaukee Road attempted to sell off divisions to raise cash. One such division was the track across South Dakota, which was sold to the State of South Dakota. The state hoped to keep the rail line in operation, whereas it was sure to shutdown in a merger. The Dakota Southern started to use the rail east of the bridge, but has dispatched any trains to the west of Chamberlain. As a result, this bridge sits largely unused.
The bridge does however still see some occasional hobby use. The hobby is restoring and running railroad motorcars, those little yellow bug-like railroad scooters and mini-cars that railroad workers used to travel over the railroad tracks for inspections and to transport small work crews. There are a surprising number of people who do this hobby. The big problem is finding a place that they can run. Most operating railroads would not allow that due to insurance reasons. An largely abandoned yet intact rail line like that running though Chamberlain is an ideal spot. A national club and a group of regional rail car clubs make the arrangements for weekend operating events. In fact, someone has posted a video on You-Tube showing a motorcar crossing the Chamberlain Railroad Bridge on August 11, 2007.