Mule deer within the Red Desert population, part of the larger Sublette herd in Wyoming, make the longest ungulate migration recorded to date in the continental United States. The southernmost mule deer within this herd travel a one-way distance of 240 km from the Red Desert in the south to the Hoback Basin and surrounding mountain ranges in the north. Their migration originates on winter ranges in the desert sagebrush habitat of the Red Desert area in southwest Wyoming. In spring, an estimated 1,000 deer travel 80 km north across the desert to the west side of the Wind River Range. From there they merge with 4,000 to 5,000 other deer that winter in the foothills of the Wind River Range and then travel a narrow corridor along the base of the mountains for 100 km before crossing the upper Green River Basin. Deer must navigate several bottlenecks, one as narrow as 50 meters wide, at the outlets of Boulder, Fremont, and Willow Lakes. In the final leg of the journey, the deer travel another 50-80 km to individual summer ranges in the mountains that drain into the Hoback Basin and Upper Green River Valley. Another segment of the herd winters in sagebrush habitats just south of the town of Pinedale and also migrate to summer ranges in the northern Wyoming Range.