Domestic Fares and Rules U.S. domestic air fares (interstate fares, and ?overseas? fares to/from U.S. territories) were deregulated by the Airline Deregulation Act of 1978, Public Law 95-504. U.S. carriers do not file their domestic passenger fares and rules with the Department.

In most modern economies, particularly in the United States and the European Union, airline pricing is largely deregulated. This means that airlines are free to set their own fares based on market demand, competition, and operational costs. In the US, the Airline Deregulation Act of 1978 removed government control over fares, routes, and market entry, which led to the "dynamic pricing" models we see today where ticket prices fluctuate by the hour. However, the government still "regulates" the way prices are displayed and handled. For instance, the Department of Transportation (DOT) requires airlines to show the "full fare," including all mandatory taxes and fees, in their initial advertisements to prevent "bait-and-switch" tactics. Additionally, while the price itself isn't capped, the government regulates consumer protection issues, such as refunds for canceled flights or compensation for being "bumped" from overbooked flights. In some countries, however—such as China or certain African nations—the government may still set "price floors" or "price ceilings" on specific domestic routes to ensure affordability or prevent predatory pricing, but the global trend remains firmly in favor of a free-market approach to airfare.