Interstate 86 (Idaho)

Interstate 86
I-86 highlighted in red
Route information
Maintained by ITD
Length	62.85 mi[1][2] (101.15 km)
Existed	1978–present
NHS	Entire route
Major junctions
West end	I-84 / US 30 near Declo
Major intersections	SH-37 in American Falls SH-39 in American Falls US 30 near Pocatello US 91 in Chubbuck
East end	I-15 in Chubbuck
Location
Country	United States
State	Idaho
Counties	Cassia, Power, Bannock
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future Idaho State Highway System Interstate US State
← I-84 → SH-87

Interstate 86 (I-86) is an east–west intrastate Interstate Highway located entirely within the state of Idaho. It runs approximately 63 miles (101 km) from an intersection with I-84 east of Declo in rural Cassia County, to an intersection with I-15 in Chubbuck, just north of Pocatello. The highway is part of the main route from Boise and Twin Falls to Idaho Falls and the upper Snake River region.

I-86 runs through a sparsely populated region along the south side of the Snake River and is mostly concurrent with US Highway 30 (US-30), which it replaced in the 1970s. It passes through American Falls at its midpoint and has a business route that serves the city center. The highway also serves Minidoka National Wildlife Refuge, Massacre Rocks State Park, the Fort Hall Indian Reservation, and Pocatello Regional Airport.

The highway follows a section of the historic Oregon Trail, which was paved and incorporated into US-30N in 1926. Under the original numbering proposal for the Interstate Highway System released in 1957, the highway was supposed to be part of Interstate 82N (I-82N), but it was instead designated as Interstate 15W (I-15W). The first section of the freeway, near American Falls, was completed in 1959. Other sections near Chubbuck and Pocatello were opened in 1968. I-15W was renumbered to I-86 in 1978, shortly before construction of its final section between Raft River and American Falls commenced. The highway was dedicated and opened to traffic on October 11, 1985.