In the early 1990s, construction of Highway 191 led to the discovery and excavation of the oldest known pronghorn kill processing site in Wyoming on the ridges below Trappers Point. Archaeologists uncovered three intact cultural layers with radiocarbon dates ranging from 4690 to 7880 years before present. Trappers Point lies in a one mile wide natural bottleneck between the Green River and Duck Creek, where thousands of pronghorn still pass each spring and fall between winter range in the south and summer ranges in the north of the Green River Basin. Analysis of fetal bones and teeth at the site indicates the pronghorn were killed here in the spring, matching modern migration patterns. Ancient people came to this spot during the spring migration to ambush pronghorn, probably hiding behind the ridge and attacking with spears or atlatl darts. Bones from the site show that pronghorn 6000 years ago were about 8% larger than modern pronghorn. More than 176,000 items were recovered, mostly pronghorn bones and stone tools such as projectile points, knives, scrapers, flakes, and fire-cracked rocks. Together with evidence of fire pits, rock boiling, bone butchering, bone beads, and awls, these finds show that prehistoric people returned to this place repeatedly over thousands of years to procure and process pronghorn. The Trappers Point Archaeology site was listed on the National Register of Historic Places in 2007, and a wildlife overpass was built on U.S. 191 in 2014 to reduce vehicle and wildlife collisions.