I-15 south at Deer Lodge Pass - Elevation 5902 Feet. This is the Continental Divide. Southbound traffic enters the Missouri River drainage (via the Big Hole River, and Jefferson River). Northbound traffic enters the Columbia River drainage (via the Clark Fork, and Pend Oreille River). I-15 crosses the Continental Divide three times in Montana. Once at Monida Pass at the Idaho-Montana state line. Here at Deer Lodge Pass, and north of Butte and Elk Park Pass.