Interstate 115 Montana
Interstate 115, similar to unsigned I-315 at Great Falls to the north, comprises a short freeway spur with a lone interchange. Totaling just 1.194 miles per the MDT 2013 Route Log, I-115 doubles as the westernmost section of the Butte Business Loop for I-15/90. The business routes extend east along Iron Street to Montana Street north beyond Exit 1.
East End – Butte, MT
West End – Butte, MT
Mileage – 1.19
Cities – Butte
- Junctions –
Source: December 31, 2018 Interstate Route Log and Finders List
I-115 Annual Average Daily Traffic (AADT)
|Location||Vehicles per day|
|I-15/90 to Excelsior Av||4,145|
|Excelsior Av to Washington St||3,190|
|Washington St to Montana St||1,898|
Source: 2018 AADT – MDT’s Interactive Traffic web map
Construction contracts to build Interstate 115 were run concurrent with the those for the I-15/90 overlap through Butte. Contracts to build a 2.6-mile section of roadway, including all of I-115, and five bridge structures were run simultaneously with completion by September 30, 1964. Contracts to construct the western 2.7 miles of I-15/90 were scheduled to December 31, 1963, and the 5.5 mile section to the east through October 15, 1964.1
The eight-mile stretch of Interstates 15/90 was dedicated on September 24, 1964. Work on the four-lane concrete freeway started in 1960 and cost $8 million.2
East End – Butte, Montana
East North at Iron Street
South West at
West End – Butte, Montana
North East at
Confirming markers for I-115 and Business Loops I-15/90 appear just ahead of the underpass carrying motorists westward along I-15/90. The roadways of the Butte freeway spur stay separate due to the terrain on the initial stretch. Photo taken by Jeff Royston (05/17/03).
West South at
West End Throwback
- Montana Highway Department. (1963). The Center line: Montana Highway Commission. Helena, MT.
- Montana Highway Department. (September, 1964). The Center line: Montana Highway Commission. Helena, MT.
Page updated August 28, 2019.