Trappers Point

PINEDALE WYOMING — Trappers Point was named for its location near the 19th century fur trappers’ rendezvous sites where mountain men gathered to trade their goods.

The narrow ridge on which an overlook is situated also forms a bottleneck on the route of the longest large mammal migration corridor in the lower 48 states.

Archaeological evidence indicates that pronghorn antelope have used this route for more than 7,000 years. Today, near Pinedale, the route includes a wildlife corridor or bridge over the highway; a project designed and constructed by the Wyoming Department of Transportation.

Journey of the Pronghorn

By Julie Francis

TRAPPERS POINT — Every year, hundreds of pronghorn antelope journey from winter range, as far south as I-80 and Green River, to summer range in Jackson Hole, a distance of about 170 miles. The Mesa’s broad, sagebrush-covered surface, with excellent visibility, is important pronghorn habitat throughout the winter.

As animals move north in the spring, they reach the narrow northern tip of the Mesa and are funneled into a bottleneck at Trappers Point. From this point, they cross U.S. 191 and continue northward up the Green River valley through another bottleneck, over the crest of the mountains, and then down the Gros Ventre River into Jackson Hole. The odyssey is repeated in reverse during the fall months.

Owing to modern agriculture and expanding residential development, other migration routes into Jackson Hole have been cut off. The Trappers Point – Green River route is the last remaining corridor. The dense concentration of game, coupled with increased traffic due to rapid expansion of the oil and gas industry on the Mesa and growth in and around Pinedale, has led to extraordinarily high numbers of animal-vehicle collisions on this stretch of U.S. 191, with significant loss of property and life (both human and pronghorn).

With glacial melting at the end of the Ice Age, the Green and New Fork rivers cut wide, deep valleys into the floor of the basin. This formed a wide plateau, known today as the Mesa, between the two rivers. This landform plays a critical role for the longest big game migration corridor in the lower 48 states.

After trying several warning systems, the Wyoming Department of Transportation built an overpass for pronghorn over U.S. 191 at Trapper’s Point. This project was done in cooperation with several state and federal agencies and local ranchers and residents. It includes a network of underpasses and one other overpass across U.S. 191 between Pinedale and a point about 15 miles north of Daniel Jct., along with a network of wildlife fencing and gates to channel animals to specific crossing points.

The Trappers Point overpass basically re-connects the northern end of the Mesa with the uplands around Cora Butte, and to pronghorns, it appears identical to the surrounding landscape. It has been an unqualified success. Even before construction was complete, animals were using the overpass.

Monitoring studies are still underway, but current information shows that over 36,000 pronghorn and deer have utilized all the crossings in just the two years since its completion.