Interstate 184 Idaho

This view of the U.S. 20-26 (West Front Street) transition into Interstate 184 westbound was taken from a centrally-located, 12-story parking garage in downtown Boise. The freeway originates from a one-way couplet (West Front Street and West Myrtle Street) that merges together here and forms the freeway. The sign shows "To Interstate 84" and indicates that the freeway carries U.S. 20-26 west. The sign does not include a shield for Interstate 184. Of the five lanes of westbound West Front Street, the left lane is a left turn only lane onto South 13th Street, the middle three lanes transition onto the freeway, and the right lane continues along West Front Street. Photo taken by David Stybr (06/03/06).


Interstate 184 is the short spur from Interstate 84 serving downtown Boise. It carries as many as eight through lanes along its short distance. It is the only three-digit Interstate Highway in Idaho.


The Boise connector has appeared in planning maps since the 1960s. It was approved as Interstate 180 by AASHTO on June 30, 1970. Some Idaho Official Maps and Rand McNally maps of Idaho showed Interstate 184 as Interstate 180N in the 1970s, referencing the time when Interstate 84 was designated as Interstate 80N prior to 1980. After I-84 was commissioned and signed, Interstate 184 in Boise was briefly signed as Business Loop I-84. This designation was ultimately eliminated as AASHTO approved the renumbering of Interstate 180 to Interstate 184 on October 13, 1979.

The following map shows the original route of Interstate 180N in Boise. This map is an excerpt from the Idaho Official State Map from 1976 (Boise strip map - note the alignments of U.S. 30 and Idaho 55, both of which have changed since 1976):

According to AARoads contributor Kelly G. Kawamoto, the interchange of Interstate 84/184 (western terminus) was reconstructed in recent years (early 2000s) to cope with an increasing traffic demand as the Boise area grows.

Highway Guide

Western Terminus - Interstate 84 and U.S. 30 - Boise, Idaho
Perspective from Interstate 84 and U.S. 30 East
Along eastbound Interstate 84 and U.S. 30, the first indication of the pending left exit split with Interstate 184 is this diagrammatic sign about two miles west of the interchange. Photo taken by Chris Elbert (07/05/05).
The split between Interstate 84 and Interstate 184 is one mile ahead. This interchange has been reconstructed in recent years to accommodate more lanes. Photo taken by Chris Elbert (07/05/05).
Use Interstate 184 east to the first exit to connect to Franklin Road, which is Exit 1 on the new freeway. Photo taken by Chris Elbert (07/05/05).
Eastbound Interstate 84/U.S. 30 will reach Exit 50A-B, Cole Road and Overland Road (right exit) immediately after Exit 49, Junction Interstate 184 east to Franklin Road (left exit). Photo taken by Chris Elbert (07/05/05).
The left three lanes depart for Interstate 184 east to downtown Boise, with a connection to Franklin Road. The middle three lanes continue straight ahead on eastbound Interstate 84, and the right lanes exit to Cole Road and Overland Road. Photo taken by Chris Elbert (07/05/05).
Perspective from Interstate 84 and U.S. 30 West
This is one of the advance warning signs along westbound Interstate 84 and U.S. 30 for Exit 49 (Interstate 184) and Exit 50 (Overland Road) in Boise. Interstate 84 and 184 directional overhead on west Interstate 84. This is a unique interchange because both Overland Road and Cole Road intersect on top of the cut and cover tunnel that crosses the freeway. This reconstructed section of Interstate 84 was completed in 1996 as part of an ongoing project to widen Interstate 84 in the Boise area due to the increasing traffic. A new three lane flyover ramp was opened in May 2000 near where these pics were taken to handle Westbound Interstate 184 to Eastbound Interstate 84 traffic replacing an old one-lane ramp. Photo taken by Steve Hanudel (05/17/06).
Perspective from Interstate 184 East
After transitioning from Interstate 84, this is the first reassurance shield along eastbound Interstate 184. Photo taken by Steve Hanudel (05/17/06).
After transitioning from westbound Interstate 84, this sign bridge indicates that the left lane will connect to eastbound Interstate 184, while the right lane exits to Franklin Road. Photo taken by Steve Hanudel (05/17/06).
Interstate 184 was reconstructed recently, with a median barrier, three through lanes of traffic, high mast lighting, and concrete paving. Photo taken by Steve Hanudel (05/17/06).
Shortly thereafter, this is the second shield along eastbound Interstate 184, with four lanes traveling toward downtown Boise. Photo taken by Steve Hanudel (05/17/06).
The second exit along eastbound Interstate 184 is Exit 3, Fairview Avenue. After this exit ramp, Interstate 184 prepares to enter downtown Boise. Photo taken by Steve Hanudel (05/17/06).
Perspective from Interstate 184 West
Now traveling west on Interstate 184 after the Cole Road interchange, westbound Interstate 184 meets Franklin Road at Exit 1A. The final interchange with Interstate 84 is Exit 0. Photo taken 08/31/06.
The left lanes and right lanes transition to Interstate 84/U.S. 30 west to Nampa/Ontario, while the middle lanes connect to Interstate 84/U.S. 30 east to Idaho Falls. Photo taken 08/31/06.
Choosing the ramp to eastbound Interstate 84 and U.S. 30 to Twin Falls, this ramp carries three lanes onto eastbound and one lane to westbound. Photo taken 08/31/06.
The three-lane ramp joins Interstate 84 and U.S. 30 east at this point. The next exit on mainline Interstate 84 is Exit 50B, Cole Road/East Overland Road. Photo taken 08/31/06.
Prior to reconstruction, this photo shows the former directional overhead on Interstate 184 westbound at Curtis Road. Interstate 184 was reconstructed along the entire freeway between 2000 and 2005. As reconstruction of each interchange is complete, the interchange received new signs and exit numbers. Photo taken by Zachary Maillard (10/00).
Eastern Terminus - Downtown Boise, Idaho
Perspective from Interstate 184 East
After the Fairview Avenue interchange, on Interstate 184 east comes to an apparent end at the point where traffic from U.S. 20-26/Chinden Boulevard merges onto the freeway. At that point, the freeway makes a turn due east and no longer carries Interstate standards. A short distance further east, U.S. 20-26 cross over the Boise River and approach the River Street offramp. All lanes have a reduced speed limit of 45 miles per hour, and the pull through lanes indicate U.S. 20-26 solely. After this turn, U.S. 20-26 revert to a surface street (Myrtle Street eastbound and Front Street westbound). Photo taken by Steve Hanudel (05/17/06).
A traffic signal ahead warning sign advises of the pending shift from freeway to city streets. U.S. 20-26 continue east to transition onto Myrtle Street. Photo taken by Steve Hanudel (05/17/06).
The highway widens as it prepares to shift onto the one-way couplet (Myrtle Street eastbound and Front Street westbound). Some vacant land separates the two directions as the highway enters downtown Boise. Photo taken by Steve Hanudel (05/17/06).
Perspective from U.S. 20-26 (West Front Street) West
To Interstate 84 and U.S. 20/26 overheads at the beginning of Interstate 184 west. Photo taken by Zachary Maillard (10/00).
To Interstate 84/West Interstate 84 at the U.S. 20/26 exit on westbound. Photo taken by Zachary Maillard (10/00).
U.S. 20/26 and TO Interstate 84 sign bridge at the beginning of Interstate 184 in Boise. Photo taken by Zachary Maillard (10/00).

Page Updated January 9, 2007.

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State Idaho
Mileage 3.62
Cities Boise
Junctions Interstate 84
Source: December 31, 2015 Interstate Route Log and Finders List
I-184 Idaho Annual Average Daily Traffic

County From: To: AADT Composite
Ada Interstate 184 Exit 1/Franklin Road 65,000
Ada Exit 1/Franklin Road Cole Road 58,000
Ada Cole Road Exit 2/Curtis Road 63,900
Ada Exit 2/Curtis Road Exit 5/Fairview Connector 52,000
Ada Exit 5/Fairview Connector Exit 4/Chinden Boulevard 62,000
Source: 2002 Rural Traffic Flow Map (ITD)