- The Blackfoot River, sometimes called the Big Blackfoot River to distinguish it from the Little Blackfoot River, is a snow-fed and spring-fed river in western Montana. The Blackfoot River begins in Lewis and Clark County at the Continental Divide, 10 miles (16 km) northeast of the town of Lincoln (4,536 ft; 1,383 m). The river’s headwaters are between Rogers Pass (5,610 ft; 1,710 m) to the north and Stemple Pass (6,376 ft; 1,943 m) to the south. It flows westward through the town of Milltown and enters the Clark Fork River approximately five miles (8 km) east of the city of Missoula (3,210 ft; 980 m).