The highway travels from an incomplete interchange with I-15/I-90 through generally rural areas in western Butte.

As a four-lane highway with two lanes in each direction, I-115 heads east into downtown Butte.

Approximately one mile (1.6 km) from I-15/I-90, I-115 has its only interchange at Excelsior Avenue, which can be used to access the town of Walkerville.

The 1955 General Location of National System of Interstate Highways, an early platform for what would become the Interstate Highway System, contained an inset of the proposed freeways in and around the city of Butte including an east–west freeway spur on the west side of the community.

[2] Designated as part of the Interstate Highway System around 1957, I-115's construction was funded by the federal government.