For regional airlines in Europe, see European regional airlines.

In the United States, regional airlines were an important building block of the passenger air system we have today. The U.S. Government encouraged the forming of regional airlines to provide feeder services from smaller communities to larger towns, where air passengers could connect to the major trunk airlines, such as American, Eastern, or United. The government also encouraged regional airline growth with the goal of making convenient air travel within the geographical reach of every American.

Regional airlines began by operating propellor-driven equipment over short routes, sometimes on stages of less than 100 miles in length.

Some examples of the original regional airlines sanctioned by the Civil Aeronautics Board in the 1940s and 1950s include:

• Frontier Airlines
• Allegheny Airlines
• Bonanza Airlines
• Mohawk Airlines
• North Central Airlines
• Piedmont Airlines
• Southern Airways
• West Coast Airlines

Many of the regional airlines eventually transitioned to jet equipment, often providing convenient passenger jet service to small communities by the 1960s and 1970s. Many of those communities lack comparable service today. Of the airlines listed above, none survives today. Some airlines use these names today; however, they are not the corporate successors to the original airlines.

In the early 21st century, regional airlines vary in ownership from being independent companies to being wholly owned subsidiaries of major trunk carriers such as American Airlines, USAirways, or Continental Airlines. Their aircraft frequently are painted in the same color scheme as the airline whose flights they support, and they exist primarily to feed passengers from smaller towns to a major airline's hub. Current regional airlines have a reputation for flying small, uncomfortable, loud and slow propellor aircraft, but many of these companies are upgrading their fleets to 30, 40, 50, and 70 passenger regional jets.