Interstate 90 in Idaho

Interstate 90 marker
Interstate 90
Purple Heart Trail
Map
I-90 highlighted in red
Route information
Maintained by ITD
Length73.888 mi[1] (118.911 km)
Existed1957–present
HistoryCompleted in 1991
NHSEntire route
Major junctions
West end I-90 at the Washington state line
Major intersections
East end I-90 at the Montana state line
Location
CountryUnited States
StateIdaho
CountiesKootenai, Shoshone
Highway system
  • Idaho State Highway System
US 89 US 91

Interstate 90 (I-90) is a transcontinental Interstate Highway that runs east–west across the northern United States. Within the state of Idaho, the freeway travels for 74 miles (119 km) from the Washington border near Spokane to Coeur d'Alene and the panhandle region at the north end of the state. After traveling through the Silver Valley along the Coeur d'Alene River in the Bitterroot Range, I-90 crosses into Montana at Lookout Pass.

I-90 was created by the federal government in 1957, following the general route of U.S. Route 10 (US 10) and the mid-19th century Mullan Road constructed by the U.S. Army. The freeway was constructed in stages between 1960 and 1992.

  1. ^ "Milepoint Log Report" (PDF). Idaho Transportation Department. Archived from the original (PDF) on July 13, 2015. Retrieved July 11, 2015.