While pronghorn are the fastest running mammals in the Lower 48 States at 60 mph, they just can’t jump a fence! Their forelegs are configured such that they will not even consider such a jump. Born to run, they are often referred to as “speed goats”.
Since they cannot jump, pronghorn choose to crawl under fences. Thus, their 150 mile migration from Grand Teton National Park to the southerly Green River Range in WY used to be quite risky. Along this route, pronghorns used to suffer many fatal collisions with vehicles. Pronghorns cross roads at the easies place for them to get under a fence, which has led them to peril.
Nowadays, there are man-made 3-rail wooden fences that funnel pronghorn to overpasses. This allows them to safely cross above a road. These overpasses span 4-lane highways and are over 100 yds long and 50 yds wide. Studies show they work well to reduce vehicle accidents with both deer and pronghorn.
Today, the pronghorn population exceeds that of humans (580k) in WY.