Allegiant Air JAC Terminal, the only commercial airport in the United States, is home to Allegiant Air's main terminal. S. . National Park. Travelers should arrive for TSA security screening and check-in at least two hours prior to departure. The terminal has a single concourse with six gates, a baggage claim area, and a number of facilities, such as a café, gift shop, and restaurant. Travelers can take in the stunning views of the mountains while they wait for their flights.