To follow Wyoming’s western boundary as much as possible on paved roads, take State Highway 89 northwest from Evanston. At Bear River, the road crosses the Utah state line. Go to Woodruff and turn north to Sage Creek Junction; from there turn right (east), cross back into Wyoming to Sage, on Highway 89. At Sage, turn north, and at Cokeville, continue northwest on 89 to Border. Now you are driving on the western boundary toward Geneva. Continue northeast on 89, then north toward Afton. Continue north to Alpine. Wyoming Highway 22 crosses the western border at Teton Pass west of Wilson, Wyo.
Finally, U.S. Hwy. 20 crosses the state boundary near West Yellowstone, Mont., and U.S. Hwy. 191 (the Gallatin Road) crosses the boundary again on its way north to Belgrade, Mont., along the Gallatin River from West Yellowstone. On the way, Hwy. 191 passes inside Yellowstone Park near the northwest corner of Wyoming, which was remonumented in 1994, but it’s a tough hike to get there.