Regional airlines have been growing quickly, taking over more flying for big-name carriers

Facts about the regional airline industry in the United States:

— LEADING REGIONALS: By 2014 traffic, among the largest are ExpressJet, SkyWest, Envoy Air and Endeavor Air. ExpressJet and SkyWest are owned by SkyWest Inc.; Envoy is owned by American Airlines Group Inc.; Endeavor by Delta Air Lines Inc.

— RAPID GROWTH: From about 15 million passengers in 1980, regional airlines carried about 162 million in 2012.

— MORE MILES: In 1980, passengers flew 1.9 billion miles on regionals. By 2012 that had soared to 75.9 billion miles.

— LONGER FLIGHTS: As regionals have taken over some longer flights once reserved for big airlines, the average trip lengthened by 264 percent.

— THEY ARE EVERYWHERE: Regionals provide subsidized service at tiny airports but also account for two-thirds of departures at Chicago's O'Hare and nearly one-third at Atlanta's Hartsfield-Jackson.

— FEWER WORKERS: Among 17 of the largest regionals, employment fell 13 percent from the equivalent of 56,626 full-time jobs in 2009 to 49,478 last year. A few were merged into other carriers or stopped flying, as in the case of former Delta subsidiary Comair.

Sources: U.S. Department of Transportation, Regional Airline Association.