The Northern Pacific Railroad was pushing west in the late 1860s and early 1870s. They reached Bismarck, North Dakota, in 1873. But that was the end of the line for almost ten years as the NP developed a strategy for moving west, and raised money for expansion. That expansion would include conquering the biggest obstacle between their home base in Brainerd, Minnesota, and the Pacific Ocean, which was the Mighty Mo River.

The NP announced in 1879 that they were building west another 200 miles to the Yellowstone River, near the Montana state line. According to the Mandan Historical Society, thousands of people moved into the Bismarck area looking for work. Many settled in a work camp just west of the Missouri River, which the the present day location of the City of Mandan.

Work began on the bridge September 1, 1881. The east truss span was finished May 9, 1882, the west span on June 3, 1882, and the center span was finished October 18, 1882. The bridge cost just over $1-million to build, which was big money in the late 1800s. The bridge features four large granite piers. The stone work on these piers give the bridge a very elegant yet sturdy look.

Early bridge photos show that the truss sections were flat on top, and they included both cables and braces in the structure. Current day photos show the truss sections to be humpback shapes that do not use cables as structural members. The truss spans were replaced in 1905 to support heavier locomotives. The rebuilt bridge was located on the 1882 piers.

The huge debt from the High Bridge and westward expansion caused real problems for the NP. It survived until a panic in 1893 pushed the railroad into backruptcy. From there, the line was bought and sold to a number of railroad tychoons, until it again went public in the 20th century. The NP name came to an end on March 2, 1970, when it merged with the Great Northern and the Chicago, Burlington, and Quincy to become the Burlington Northern. The BN later merged with the Santa Fe Railway to become the BNSF, the current owners of the High Bridge. Rail traffic dropped on the high bridge after the 1970 merger when the BN used the former GN mainline in favor of the NP mainline. Traffic on the NP mainline and the High Bridge have dramatically increased in recent years due to long unit trains hauling coal out of the Powder River Basin in Wyoming.