I-15 passes Market Lake Wildlife Management Area ahead of its diamond interchange with SH 23 at Sage Junction. The highway has a diamond interchange with Hamer Road at Hamer and briefly passes through the Camas National Wildlife Refuge and crosses Camas Creek, which flows into Mud Lake. I-15 follows a tributary of Camas Creek, Beaver Creek, into Clark County and its county seat of Dubois, where the Interstate meets the eastern end of SH 22 at a diamond interchange. North of Dubois, the freeway has a partial cloverleaf interchange with Sheep Station Road that serves the U.S. Sheep Experiment Station. I-15 continues along Beaver Creek through a diamond interchange at Spencer as the Interstate enters the Bitterroot Range. The Interstate enters Targhee National Forest and has diamond interchanges with Stoddard Creek Road and at Humphrey. I-15 reaches its northern end in Idaho at Monida Pass, where the highway crosses the Continental Divide into Beaverhead County, Montana.