This data set contains large mammal migration routes for five ungulate species (elk, mule deer, bighorn sheep, moose, and pronghorn) in the Greater Yellowstone Ecosystem, as compiled from GIS data on migration route locations for Wyoming, Montana, and Idaho. Each route is assigned a confidence ranking, a threat score and mean threat value based on the likelihood of adverse impacts from human land use along the length of the route (Lyons 2006).