The river flows west out of the mountains and then northward along the border of Wyoming and Idaho. It passes  Smoot, Wyoming and then meanders through the mostly agricultural Star Valley, being joined by numerous creeks along the way, to its confluence with the Snake River near the town of Alpine (elevation ).
Flowing from the mountains in a westerly direction, the river continues northwards along the Wyoming-Idaho border. It passes through Smoot, Wyoming, and then winds its way through the agricultural Star Valley, merging with numerous smaller streams as it approaches its junction with the Snake River near Alpine.