Interstate 184 and 86 in Idaho

Interstate 184 in Idaho

Get started Meridian
End Boise
Length 4 mi
Length 6 km
0 → Nampa / Salt Lake City1A Franklin Road

1B Cole Road

2 Curtis Road

3 Chinden Boulevard

4 Downtown Boise

Interstate 184 is a short Interstate Highway in the U.S. state of Idaho. The highway connects downtown Boise with Interstate 84. The highway has 2×3 lanes and is 6 kilometers long. The last stretch of I-184 is double numbered with US 20/26.

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Travel directions

I-184 begins at a spacious interchange with Interstate 184 in western Boise. The highway then has 2×3 lanes and heads east, further into the city of Boise. The US 20 / US 26 connect at Garden City. I-184 then crosses the Boise River, after which the highway ends on the west side of Downtown Boise on two one-way roads with 4 lanes each.


Originally, Boise had two approach roads from the west, US 30 from Nampa and Meridian, and connecting US 20 / US 26 from Caldwell a little further north. I-184 was constructed in the latter half of the 1960s and was largely opened on December 12, 1968. This was a 5 kilometer stretch from I-84 to US 20/26. The viaduct over the Boise River and thus the extension to the center of Boise was built much later, presumably in 1989.

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There may have been plans in the past to widen I-184 through downtown, satellite images from the early 1990s show that much of the route past Broadway Avenue was undeveloped, while other blocks outside of this route were largely built-up.

I-184 was originally numbered I-189N, the only three-digit Interstate Highway with a suffix. The highway was opened to traffic on December 12, 1968.

In the early 2000s, I-184 was widened to 2×3 lanes. The interchange with I-84 has also been reconstructed. This was originally a three-branch junction with left-hand in and outs. This has been converted to regular connecting roads and flyovers. Special is the 3-lane flyover from Downtown towards I-84 East.

Interstate 86 in Idaho

Begin Declo
End Pocatello
Length 63 mi
Length 101 km
1 → Boise / Salt Lake City15 2880 East Road

21 Barkdull Road

28 Massacre Rocks State Park

33 Rock Creek Road

36 Rockland Highway

40 American Falls

44 Ramsey Road

49 Gas Line Road

52 Arbon Valley Highway

56 Pocatello Airport

58 Pocatello

62 Pocatello

63 → Salt Lake City / Butte

Interstate 86 (west) or I -86 is an Interstate Highway in the United States, located entirely in the state of Idaho. The highway provides a short connection in the south of the state from I-84 at Declo to I-15 at Pocatello. I-86 is 101 kilometers long.

Travel directions

The I-86 at American Falls.

In the wasteland of southern Idaho, I-86 exits from Interstate 84 at the village of Declo, which runs from Boise toward Salt Lake City. One comes across the Snake River Plains, a plain with mountains on the south side. The journey is quite monotonous, with hardly any trees. The only place on the way is the village of American Falls. You then arrive at Pocatello, one of the largest towns in Idaho with a population of 54,000. Here the highway connects to Interstate 15.


I-86’s predecessor was US 30, which was numbered US 30N at the time, since there was also a US 30S from Burley to the Utah border, where I-84 was built parallel to it.

Few exact details of the construction of I-86 are known. Construction, like almost all Interstate Highways in Idaho, began in the early 1960s, and by 1964 the first two sections were opened, the westernmost section from Declo beyond Raft River, and the American Falls bypass. At the time, I-84 became I-86, the interchange was built later. Construction of I-86 was the lowest priority of all Interstate Highways in Idaho. By 1969, the Pocatello bypass had opened and the American Falls bypass had been extended a short distance toward Pocatello. In late 1969, the interchange with I-84 also opened at Declo. Around 1973, the missing section opened up between American Falls and Pocatello. It is not known exactly when the missing section between Raft River and American Falls was opened, presumably in the late 1970s or early 1980s. This was one of two missing sections of Interstate Highways in Idaho after 1974 (the other being I-90 through Wallace).

The highway was originally numbered as I-15W, a branch of Interstate 15. In 1980, the highway was renumbered to I-86.

Traffic intensities

The I-86 is a very quiet highway, the western part has only 6,500 vehicles per day, which peaks at 22,000 vehicles per day at Pocatello.

Interstate 86 in Idaho