In 1875, this Army Bridge spanned a much broader and more turbulent river than it does today. Back then, high water made it nearly impossible to cross the North Platte River near Fort Laramie, Wyoming for several months each year. When the Fort Laramie Treaty was signed in 1868, provisions for the newly established Indian agencies were in high demand. To make sure supplies could be transported, Congress funded the construction of this iron bridge near Fort Laramie. Unfortunately, thousands of fortune hunters began using the bridge when gold was discovered in the Black Hills, crossing into Indian territory which violated the 1868 Treaty. This violation eventually led to open warfare, and by 1876 the military had control of the bridge and used it to move troops and supplies. Ultimately, the tribes were overpowered and their lands were taken. It was the end of an era.
The Old Army Bridge is one of the last remaining examples of a three-span bowstring through truss bridge and is now only open to foot traffic. A new highway bridge was built in 1958.