Ancient Highways Built for Pronghorns

Every year, pronghorn antelope in Wyoming make one of the longest land migrations in the lower 48 states, traveling roughly 150 miles each way between their summer range near Grand Teton National Park and their winter grounds in the Red Desert. They follow the same corridors their ancestors have used for thousands of years. When highways were built across those routes, hundreds of pronghorn were killed by vehicles each year and many more were blocked by fences with no way through. Wyoming's solution was clever: conservationists installed long drift fences along Highway 191 near Pinedale to guide the herds toward purpose-built underpasses rather than into traffic. The pronghorn found the crossings within the first season and vehicle collisions dropped dramatically. The pronghorn itself is a remarkable animal: the fastest in the Western Hemisphere and second only to the cheetah worldwide, capable of sustaining 55 miles per hour over long distances. That speed is thought to be a ghost adaptation, evolved to outrun the American cheetah, a predator that went extinct 12,000 years ago and no longer exists.