Interstate 86 (Western)
The Western Interstate 86 is a rural route linking Interstate 84 east of Twin Falls with Interstate 15 at Pocatello in southeastern Idaho. The freeway parallels the Snake River (Lake Walcott) northeast from Raft River to American Falls. East from there, the route flattens out somewhat adjacent to a Union Pacific Railroad line to the Pocatello vicinity.
There is an eastern Interstate 86, stretching from Erie County, Pennsylvania across the Southern Tier of New York. That route was established in 1999. Prior to that, a second I-86 ran from Hartford, Connecticut to Sturbridge, Massachusetts from 1969 to 1984. Other split routes include Interstates 76, 84 and 88.
Parallel U.S. Routes
Interstate 86 follows U.S. 30 (former U.S. 30N) throughout its route in Idaho and has one business loop in American Falls.
Interstate 15W was initially to be renumbered as part of newly designated Interstate 84 from Pocatello west to the junction with Interstate 80N; I-86 was the number preferred by Idaho and Utah officials for the I-80N corridor. Instead, AASHTO conditionally approved the renumbering of I-15W as I-86 and I-80N as I-84 on July 6, 1977. Approval of the renumbering was finalized by November 1977 and sign changes were to be made by January 1, 1978.1
Interstate 15E was completed from I-80N east to the Power County line and west from Pocatello to Idaho 37 (Exit 36) outside American Falls. Completion of the freeway directly over laid the remainder of two-lane U.S. 30 along the Snake River.
East End – Pocatello, ID
- West End – Declo, ID
- Branch Routes – 0
Mileage – 62.85
Cities – American Falls, Pocatello
- Junctions –
Source: December 31, 2017 Interstate Route Log and Finders List
I-86 Annual Average Daily Traffic (AADT)
|Location||Vehicles per day|
|I-84 to Exit 15||6,400|
|Exit 15 to Exit 21||6,400|
|Exit 21 to Exit 28||6,400|
|Exit 28 to Exit 33||6,400|
|Exit 33 to Exit 36||6,500|
|Exit 36 to Exit 40||6,300|
|Exit 40 to Exit 44||9,900|
|Exit 44 to Exit 49||9,900|
|Exit 49 to Exit 52||10,000|
|Exit 52 to Exit 56||11,000|
|Exit 56 to Exit 58||12,500|
|Exit 58 to Exit 61||11,000|
|Exit 61 to Exit 63 (I-15)||20,500|
Source: Source: 2002 Rural Traffic Flow Map (ITD)
Interstate 15W was renumbered as Interstate 86 three years before sign changes were made along I-80N. Both renumberings were approved by AASHTO in 1977.
East End – Pocatello, Idaho
Western – near Declo, Idaho
- "Interstate 80 to become 84." The Deseret News, August 13, 1977.
Page updated June 9, 2015.