is a business loop of Interstate 15 (I-15) in Cascade County, Montana, United States, almost entirely within Great Falls.

The southernmost 0.83 miles (1.34 km)[1] of the route from the interchange with I-15 to Fox Farm Road is designated, but not signed, as Interstate 315 (I-315).

begins at I-15 exit 278 in an unincorporated area of Cascade County, a short distance southwest of Great Falls.

The Interstate Highway standard conditions come to an end a short distance to the east at an intersection with Fox Farm Road.

[3] Within downtown, the four routes remain concurrent along 10th Avenue South to the parallel one-way couplet of 5th and 6th streets.

follows Central Avenue to the west, crossing the Missouri River once more as it exits downtown.