Mullan Road was the first wagon road to cross the Rocky Mountains to the Inland of the Pacific Northwest. It was built by U.S. Army troops under the command of Lt. John Mullan, between the spring of 1859 and summer 1860. It led from Fort Benton, which at the time was in the Dakota Territory, then Idaho Territory from July 1863, and Montana Territory beginning in May 1864, and the navigational head of the Missouri River (and once farthest inland port in the world). The road connected to Fort Walla Walla, Washington Territory, near the Columbia River. The road previewed the route approximately followed of modern-day Interstate 15 and Interstate 90 through present-day Montana, Idaho, and Washington. Parts of the Mullan Road can still be traveled; one such section is near Washtucna, Washington. A segment of the Mullan Road in the vicinity of Benton Lake was listed on the National Register of Historic Places in 1975, and the American Society of Civil Engineers designated it a National Historic Civil Engineering Landmark in 1977. Three segments of the road in Idaho were also listed on the National Register in 1990. In 2009, the Point of Rocks segment in Montana was also listed on the National Register as part of the Point of Rocks Historic Transportation Corridor. History 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. Despite the Lewis and Clark expedition, little detail was known about the country. Isaac Ingalls Stevens, a West Point graduate appointed the first governor of the Washington Territory, was ordered to survey a route from the Missouri River to the Columbia River suitable for building a railroad. Stevens assumed the task, but also kept in mind that the route should be suitable for a wagon road. In the spring of 1853, Congress authorized a U.S. Army expedition, led by Stevens. It was made up of engineers and explorers; they organized near St. Paul, Minnesota. They were to detail the geographical and topographical character of the country. 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. Mullan was placed in charge of surveying, and later improving,