Yellowstone National Park is served by airports in nearby communities, including Cody, Wyoming, one hour east; Jackson, Wyoming, one hour south; Bozeman, Montana, 90 minutes north; and West Yellowstone, Montana, just outside the park's west gate, which has only summer service. The best places to rent cars in the region are at airports in Cody, Jackson, Bozeman, and West Yellowstone. There is no commercial bus service to Yellowstone.
Yellowstone is well away from the interstates, so drivers make their way here on two-lane highways that are long on miles and scenery. From Interstate 80, take U.S. 191 north from Rock Springs; it's about 177 mi to Jackson, then another 60 mi north to Yellowstone. From Interstate 90, head south at Livingston, Montana, 80 mi to Gardiner and the park's North Entrance. From Bozeman travel south 90 mi to West Yellowstone.
Yellowstone has five primary entrances. The majority of visitors arrive through the South Entrance, north of Grand Teton National Park and Jackson, Wyoming. Other entrances are the East Entrance, with a main point of origin in Cody, Wyoming; the West Entrance at West Yellowstone, Montana (most used during winter); the North Entrance at Gardiner, Montana; and the Northeast Entrance at Cooke City, Montana, which can be reached from either Cody, Wyoming, via the Chief Joseph Scenic Highway, or from Red Lodge, Montana, over the Beartooth Pass.
The best way to keep your bearings in Yellowstone is to remember that the major roads form a figure eight, known as the Grand Loop, which all entrance roads feed into. It doesn't matter at which point you begin, as you can hit most of the major sights if you follow the entire route.
The 370 mi of public roads in the park used to be riddled with potholes and had narrow shoulders -- a bit tight when a motor home was pulled over to the side to capture wildlife or scenery on film. But because of the park's efforts to upgrade its roads, most of them are now wide and smooth. Road work is ongoing in a few areas, including a segment of the East Entrance Road over Sylvan Pass, with half-hour delays most days and complete nighttime closures through 2007. On holiday weekends, road construction halts so there are no construction delays for travelers. Check with park rangers to determine where you'll encounter delays or closures. Snow is possible any time of year in almost all areas of the park.