A segment of the Mullan Road in the vicinity of Benton Lake was listed on the National Register of Historic Places in 1975,[3] and the American Society of Civil Engineers designated it a National Historic Civil Engineering Landmark in 1977.

As early as 1852 the US government began to think about building an overland route to the Pacific Ocean to help settle the area with pioneers and eliminate any claims that France, England or Russia had on the disputed territories.

Among them was a small, dark-haired young man, Lieutenant John Mullan; just a year out of West Point, he was anxious to prove his mettle as an engineer.

Lieutenant Mullan commanded a workforce of more than 200, including civilian workers, surveyors, engineers, and soldiers who carved a 25-foot-wide (7.6 m) road across the region.

[4][5] Although the road was never heavily used by the military, it was an important conduit for civilian passage, which hastened settling of the northwestern United States.

The road continued to serve as an important route until the completion of the Northern Pacific Railroad in 1883 provided faster and more convenient access to the region.