Additional Info

Mileage

State Idaho
Mileage 62.85
Cities American Falls, Pocatello
Junctions I-84, I-15
State Pennsylvania
Mileage 6.99
Cities None
Junctions I-90
State New York
Mileage 216.40
Cities Jamestown, Olean, Hornell, Bath, Corning, Elmira
Junctions I-390, I-99
TOTAL 286.24
Source: December 31, 2016 Interstate Route Log and Finders List
I-86 Idaho Annual Average Daily Traffic
From: To: AADT Composite
I-84 Exit 15/ Raft River 6,400
Exit 15/ Raft River Exit 21/ Coldwater 6,400
Exit 21/ Coldwater Exit 28/ Massacre Rocks 6,400
Exit 28/ Massacre Rocks Exit 33/ Neely 6,400
Exit 33/ Neely Exit 36/ West American Falls 6,500
Exit 36/ West American Falls Exit 40/ East American Falls 6,300
Exit 40/ East American Falls Exit 44/ Seagull Bay 9,900
Exit 44/ Seagull Bay Exit 49/ Rainbow Road 10,000
Exit 49/ Rainbow Road Exit 52/ Arbon Valley 10,000
Exit 52/ Arbon Valley Exit 56 /Air Terminal 11,000
Exit 56/ Air Terminal Exit 58/ West Pocatello 12,500
Power/Bannock Exit 58/ West Pocatello Exit 61/ Chubbuck 11,000
Bannock Exit 61/ Chubbuck Exit 63/ I-15 20,500
Source: 2002 Rural Traffic Flow Map (ITD)
Southeast Idaho - 1973 Idaho Official Highway Map.
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.
Southeastern Idaho - 1978 Idaho Official Highway Map.
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.
Former button copy sign predating the 1980 change of Interstate 15W to 86 on I-84 & U.S. 30 east. Photo taken by Jeff Royston (07/11/07).

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Interstate 86 (Western)

Routing

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 through 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).

History

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

An excerpt from the 1976 Idaho Official Highway Map showing the interchange array along Interstate 15W (now Interstate 86).

Western Terminus - Interstate 84 - near Declo, Idaho
Perspective from Interstate 84 and U.S. 30 east
Vintage button copy sign on I-84 east for Interstate 86and the split with U.S. 30. Photo taken by Jeff Royston (07/11/07).
The Interstate 84 mainline defaults onto I-86 & U.S. 30 east toward American Falls. I-84 makes a TOTSO (turn off to stay on) movement at the forthcoming exchange. Photo taken by Jeff Royston (07/11/07).
Interstate 84 angles southeast to Tremonton, Utah, where it combines with I-15 to Ogden. I-84 parallels the Snake River east to Bannock. Photo taken by Jeff Royston (07/11/07).
Perspective from Interstate 84 west
The first advance signage for Interstate 86 and U.S. 30 (Exit 222) appears two miles out along I-84 westbound. Photo taken by Steve Hanudel (05/17/06).
Westbound Interstate 84 meets I-86 and U.S. 30 at Exit 222. I-86 & U.S. 30 east overlap to American Falls and the west side of Pocatello. U.S. 30 west joins I-84 to Heyburn. Photo taken by Steve Hanudel (05/17/06).
Eastern Terminus - Interstate 15 - Pocatello, Idaho
Perspective from Interstate 86 east
The first sign for Interstate 15 along I-86 east precedes the diverging diamond interchange (DDI) with U.S. 91 (Yellowstone Highway). Photo taken by Jeff Royston (07/11/07).
Exit 61 departs for U.S. 91 (Yellowstone Highway) to Chubbuck and Pocatello. Exits 63A/B follow for Interstate 15 north to Idaho Falls and Butte, Montana and south to Ogden and Salt Lake City, Utah. Photo taken by Jeff Royston (07/11/07).
Advancing east toward the trumpet interchange (Exit 63) with Interstate 15. Photo taken by Chris Elbert (03/06).
Exits 63A/B partition at the east end of Interstate 86. Photo taken by Chris Elbert (03/06).
Perspective from Interstate 15 south
Former button copy sign posted two miles ahead of Interstate 86 west (Exit 72). Photo taken by Chris Elbert (03/06).
A half mile north of Exit 72 with I-86 west to American Falls, Twin Falls and Boise. Photo taken by Chris Elbert (03/06).
Southbound Interstate 15 reaches Exit 72, Interstate 86 west to American Falls and Twin Falls. The next exit is Exit 71, Business Loop I-15 south into downtown Pocatello. Photo taken by Chris Elbert (03/06).
Perspective from Interstate 15 north
Exit 71 leaves I-15 north for Pocatello Creek Road, one mile ahead of the trumpet interchange (Exit 72) with Interstate 86 west. Photo taken by Kelly G. Kawamoto (08/00).
The connection from Interstate 15 north to Interstate 86 west is a left exit. Photo taken by Chris Elbert (03/06).
Northbound Interstate 15 reaches Exit 72, Interstate 86 west to American Falls and Interstate 84 west to Twin Falls, Boise, and Portland, Oregon. Photo taken by Chris Elbert (03/06).

Sources:

  1. "Interstate 80 to become 84." The Deseret News, August 13, 1977.

Page Updated June 9, 2015.