I-184 begins at the "Flying Wye" interchange with I-84 and US 30 in southwestern Boise. The six-lane freeway travels northeast through suburban Boise, crossing over a spur railroad near an interchange with Franklin Street on the south side of the Boise Towne Squareshopping mall. I-184 intersects Curtis Road near the Saint Alphonsus Regional Medical Center and turns due east along Fairview Avenue, which acts a frontage road. On the west side of the Boise River in Rotary Park, I-184 terminates after an interchange with US 20 and US 26, which serve northwestern Boise on Chinden Boulevard. US 20 and US 26 supersede I-184 and cross into Downtown Boise, where it splits into Front and Myrtle streets. Interstate 184 is the only three-digit Interstate route in Idaho and the state's shortest, at. The highway is maintained by the Idaho Transportation Department, which conducts an annual survey of traffic on certain highway segments that is expressed in terms of average annual daily traffic, a measure of traffic volume for any average day of the year. The sole traffic recording device on I-184 reported a daily average of 81,140 vehicles on the highway in 2017.
History
The Boise Connector was planned in the early 1960s to connect the Boise freeway bypass to downtown Boise and its inner neighborhoods. One version of the plan proposed a full loop bisecting downtown Boise to carry Interstate 80N, but it was rejected in favor of a less costly spur route. The westernmost section of the connector, including a sprawling wye interchange with I-80N, was opened to traffic on December 12, 1968, a year before the rest of the bypass. Parts of the connector were signed as part of SH-55 until it was realigned in the 1980s. The freeway was numbered Interstate 180N until October 13, 1979, when I-184 was adopted to match I-84, which was planned to succeeded I-80N. It was the only signed suffixed auxiliary Interstate route in the nation. When Interstate 80N was redesignated Interstate 84, this highway was re-designated Business Loop I-84 through Boise. The current I-184 designation was signed when the construction upgrading the route to Interstate standards was completed in 1990. The new bridge across the Boise River was opened on August 7, 1992, replacing a pair of smaller bridges to the north. The westernmost segment of I-184, including the Flying Wye interchange, was rebuilt from 1999 to 2004 to accommodate an additional set of lanes. The project cost $86 million and was delayed several times due to a dispute with the Environmental Protection Agency.
