(197 mi): You can get to Idaho Falls via West Yellowstone, as above, or you can go via Ennis. Although the mileage is a little bit more, the road is not as windy, so you'll make better time and encounter less traffic. To go that way, from the Inn drive north on S. Willson Ave. 4 blocks to Main Street. Turn left (west) on Main Street (US-191.) Drive 10.5 miles on US-191 to Four Corners. When you get to Four Corners, rather than turning left towards West Yellowstone, go straight on US-84 towards Norris & Ennis, 42 miles. When you reach US-287 turn left and drive through Norris, Ennis and Cameron until you reach US-87. Turn right on US-87 and drive until you reach US-20, about 10 miles. Turn right on US-20 and drive all the way to Idaho Falls, about 90 miles. Both routes are beautiful drives, so which way you go just depends upon time and whether you want beautiful rolling hills, wide vistas and the Madison river (route via Ennis) or a beautiful windy road along the Gallatin River through the woodsy Gallatin Canyon (route via West Yellowstone.) Either way, you can't lose!