As the days lengthen and spring flowers bloom, herds of pronghorns in Wyoming migrate north from their winter grounds in the Upper Green River Basin to Grand Teton National Park. The journey, which biologists have dubbed the "Path of the Pronghorn," covers about 150 miles across government and private lands. Pronghorns have walked this route since prehistoric times, though today, fences, highways, and other unnatural barriers have made the journey more perilous. To mitigate these dangers, wildlife corridors are being constructed over highways and under bridges, offering safer passage for these quintessential symbols of the American West. Conservation efforts like these have helped to make the "Path of the Pronghorn" one of the longest migration corridors remaining for large mammals in North America.