For more than one hundred years, the Green River Drift cattle trail has connected seasonal communal grazing lands with cattle ranches in the Upper Green River Valley. Area ranchers move livestock along the trail with cowboys on horseback, taking cattle from spring grazing at the southern end to summer grazing at the northern end and back to home ranches in the fall. Experienced mother cows help lead herds toward greening grass at higher elevations and back down as the weather cools. This seasonal movement of cattle from the Little Colorado Desert to the upper reaches of the Green River became known as the Drift and coincides with the migration of deer and antelope between mountain and valley habitats. The trail was already in use when the Equalizer Winter of 1889-1890 established the Drift as an economic and environmental necessity after that harsh winter killed 90 percent of the valley's cattle. Ranchers then used summer meadows to raise hay while cattle grazed open range under cowboy supervision, and cattle returning in the fall were sustained through winter by the homegrown hay crop. As rangeland shifted to federal agency management in the early twentieth century, a monitored system was created to move cattle through allotments from Bureau of Land Management units in the valleys to the Bridger-Teton National Forest. Once stretching 150 miles from Fontenelle Creek south of LaBarge, Wyoming, to Green River Lakes, the trail today extends about 68 miles and is used in much the same way as a century ago. The Drift has endured through cooperation among private landowners, federal land management agencies, and participating ranches. Its most visible feature is the Drift Fence, a large fenced sorting ground around Trapper's Point south of US 191, built in 1921 with World War I wire. In spring and fall, cattle and wildlife move through the Drift Fence on their way to and from the mountains, using a nearby underpass and overpass. During the fall gather, cattle drifting down from the mountains are contained there, and for two or three weeks cowboys sort them by brand into separate ranch herds each morning. Cattle from nearby ranches are trailed home, while cattle from more southerly ranches continue down the trail past Sommers Homestead to be sorted and collected near State Highway 351. Preserving the trail northward has been difficult as open range gave way to Bureau of Land Management allotments and deeded private land, narrowing the route and complicating its connection to U.S. Forest Service grazing land. The first underpass was built in 1939 after construction of US Highway 191 created a barrier for livestock and wildlife. North of US 191, a private land donation from the Carroll Noble family created Noble Lane, preserving the trail along State Highway 352 past Cora. The route then widens across Bureau of Land Management land between Wright Hill and Marsh Creek, where cattle can reach water and forage, passes under Highway 352 at Marsh Creek, and enters the Bloom Driveway, built by the Civilian Conservation Corps in 1938. From the Drift Fence to the forest, the trail crosses both private land and a specially designated Bureau of Land Management livestock driveway.