The North Bighorn mule deer herd inhabits the northern half of the Bighorn Mountains in north-central Wyoming (fig. 28). The herd consists of resident mule deer that live year round in lower elevation foothills (approximately 4,265 ft [1,300 m]), primarily on private, Wyoming State trust, or BLM lands, and migratory mule deer that travel from the foothills to the summer ranges at higher elevations (approximately 7,874 ft [2,400 m]) on the Bighorn National Forest. In general, annual precipitation across the mountain range increases with elevation. To the west of the Bighorn Mountains, the Absaroka Range and arid Bighorn Basin, which receives only 7 in. (18 cm) of rain annually, prevents moisture-laden winds from reaching the western slopes of the Bighorn Mountains; therefore, the western side of the Bighorn Mountains generally receives less precipitation than the eastern side (Nesser, 1986). At lower-elevation (approximately 4,265 ft [1,300 m]) winter ranges, the western side of the mountain range comprises primarily sagebrush-steppe, whereas the eastern side consists primarily of grassland and agriculture. Mule deer have vastly different migration strategies depending on where they winter; most mule deer that winter on the eastern side of the mountain range are residents (76 percent), whereas most mule deer that winter on the western side of the mountain range are migratory (97 percent). Summer ranges at high elevations on Bighorn National Forest lands comprise primarily coniferous forest, most commonly lodgepole pine followed by Picea engelmannii (Engelmann spruce) and Abies lasiocarpa (subalpine fir; Witt, 2008). The herd is threatened by competition from increasing elk and white-tailed deer populations and expanding CWD prevalence (Wyoming Game and Fish Department [WGFD], 2022). These mapping layers show the location of the migration routes for mule deer (Odocoileus hemionus) in the North Bighorn population in Wyoming. They were developed from 355 migration sequences collected from a sample size of 176 animals comprising GPS locations collected every 2 hours.