The river rises on the northern side of the
Uinta Mountains in the
Uinta-Wasatch-Cache National Forest in
Summit County, Utah, as the combination of three streams draining the area around Tokewanna Peak near the Utah–Wyoming border. Just before the river crosses into Wyoming, it flows into
Meeks Cabin Reservoir, which is used for irrigation and flood control. After entering
Uinta County in Wyoming and then flowing out of the reservoir, the river leaves the national forest. It then flows northeast through
unincorporated community of
Millburne and along the edge of the
census-designated place of
Fort Bridger. Turning to a nearly eastern course, the river passes under
Interstate 80 (I‑80) before joining with the Smiths Fork (possibly named for
Jedediah Smith), which forms just east of the Blacks Fork in the Uinta Mountains and parallels it for most of its course. The river continues northeast, very briefly passing through the extreme southeast corner of
Lincoln, Wyoming, (where it turns east) before entering
Sweetwater County, Wyoming. The river then meets the Hams Fork from the north on the southwest edge of
Granger. Promptly after entering Granger, the river passes along the south edge of the
Granger Stage Station and then passes under
U.S. Route 30 (US 30). Shortly after that, the river makes sharp turn south (passing under I‑80/US 30) and eventually entering the
Flaming Gorge National Recreation Area and joining the Green River at
Flaming Gorge Reservoir ==History==