Jan.24.2021 Bid boring goodbye on Interstate 25 in Wyoming, one of the nationâs most beautiful interstates. Nature gave the buttes crew cut hairdos. The gap between the Laramie Mountains and the Big Horn Mountains was the pioneersâ path to the west. Between Kaycee and Sheridan, the Bighorn National Forest stretches beside the highway. Allow at least a day in Cheyenne, then two more days to explore the rest of I-25âs stops. Drive time without stops is 4.5 hours. I-25 roughly follows the Bozeman Trail, the only trail that indigenous peoples ever shut down permanently. Range wars pitted homesteaders and large ranchers against each other.