Jackson Hole Airport (JAC) is the only commercial airport inside a national park in the United States, set between Grand Teton National Park and the National Elk Refuge. It has year-round direct flights to Denver, Salt Lake City, Dallas, Los Angeles, New York, and Chicago, with additional seasonal routes in winter (ski season) and summer. The airport is 13 km north of the town of Jackson.
By car, Jackson is reached via US-191/US-89 from Rock Springs to the south (about 3 hours from Salt Lake City) or from Yellowstone and Grand Teton to the north. The Teton Pass (Highway 22) from Idaho can close in winter storms — check road conditions before attempting it. There is no long-distance bus service to Jackson that makes practical sense. Amtrak's California Zephyr stops at Rock Springs, from which you would need to arrange further transport.