The Mullan Military Road - Celebrating 150 Years of Transportation In & Out of The Coeur d' Alene Mining District - "IT'S ALL ABOUT THE MINERALS!!!"
"Had not the John Mullan Military Road been driven through this section of Shoshone County, there would probably not have been many humans in the area to discover and stake lode claims until well into the 20th Century."
"History of Idaho's Silver Valley 1878 - 2000", Ray Chapman.
It's a Tough Place to Maintain a Road
It's Harsh Terrain. The whole district is one vast bed of mountains. The valley is nothing more than a gorge. There are no difficult hills, but several swamps and marshy places, wherein the road is very bad. The stream (Coeur d' Alene River) is crossed 47 times. The summit of the ridge is 1600 feet above its base. Lt J. L. White, Mullan road building party, 1861.
It Snows A Lot. Lookout Pass / Sohon Pass area receives an average of over 400 inches (over 33 feet) of snow each winter. The snow precipitates avalanches and winter storms knock down hundreds of trees each winter.
It Floods. Heavy rains and snow melt combine for major flooding throughout the district. The 20 some odd bridges built in the district on the original Mullan Road were all washed out by the mid 1860's. The worst flood on record was in January 1974 where a portion Interstate 90 was washed out causing over $10 million in damages. The spring runoff of 2008 saw a portion of the Trail of the Coeur d' Alenes washed out near Harrison, Idaho (1859 Mullan Road route).