State Highways in Idaho

Interstate 184 (I-184) is a short Interstate Highway spur route of Interstate 84 located in Idaho. I-184 connects I-84 travelers to downtown Boise. The western terminus of I-184 is with I-84; the eastern terminus 13th Street in downtown Boise, where I-184 empties eastbound traffic onto Myrtle Street and receives westbound traffic from Front Street. The Front/Myrtle couplet passes just south of the heart of downtown Boise and connects to Broadway Avenue 1/4 mile north of Boise State University. Between Chinden Boulevard and its eastern terminus I-184 is co-signed with U.S. Highway 20 and U.S. Highway 26.

Until 1980, the freeway was known on paper as Interstate 180N, when Interstate 84 was known as Interstate 80N. This was the only signed suffixed auxiliary Interstate route in the nation, though it was not upgraded to Interstate standards until after the parent route was renamed. Other suffixed routes around the country either were too short to merit an auxiliary route or used the unsuffixed route number for its auxiliary routes. This was illustrated by Interstate 80S in Pennsylvania, whose auxiliary routes were I-180, I-280, I-480, and I-680 respectively.

When Interstate 80N became Interstate 84, the road became Business Loop I-84 through Boise. The current I-184 designation was implemented when the construction upgrading the route to Interstate standards was completed in 1989.

Interstate 184 is the only three-digit interstate route in Idaho.

The entire route is in Boise, Ada County.