The Mullan Road, constructed between 1858 and 1862, was the first wagon road to cross the northern Rockies to the Inland Northwest.

The building years were a momentous time in the history of the inland Northwest. The United States Army had just fought the Coeur d'Alene War (1858). The section of the trail in eastern Washington passed by the sites of the recent war, including "Pyramid Butte" (site of the Battle of Steptoe Butte), Hangman Creek (where Col. George Wright summarily executed several Indians), and "Horse Slaughter Camp" (where Colonel Wright slaughtered 700 horses, owned by the local tribes). In his report on the road-building (see below), the reader can discern Capt. John Mullan's concern that his expedition would encounter still-hostile Indians

The story of the Mullan Road provides a window onto many historical topics including American road-building, the Indian history of the Inland Northwest, the American wilderness, the white settlement of the Inland Northwest, and the story of America at the mid-nineteenth century, including the Civil War.

In 1863, Capt. John Mullan published a comprehensive account of the building of the road. 

Mullan Road Report 1861 can be veiwed Here with a summary of the report Here.