Analysis: The US 'Big 3' Legacy Carriers' Shortest Mainline & Regional Domestic Flights

As one of the world’s largest countries by population and land mass, the United Stateshas a huge and diverse network when it comes to domestic aviation. The nation is home to some of the longest internal flights in the world, particularly those serving Hawaii or transcontinental routes, but what about the shorter side of things? As it happens, there are also plenty of domestic routes that fit this bill by clocking in at under 100 miles.

Using current scheduling data made available by Cirium, an aviation analytics company, let’s take a look at the shortest US domestic routes by distance this November that are being operated by the ‘big three’ legacy carriers: American Airlines, Delta Air Lines, and United Airlines. We will do so by examining both the shortest mainline internal routes operated by these carriers, as well as those served by their regional feeder partners.

American Airlines

Starting with American Airlines, the Fort Worth-based oneworld founding member’s shortest mainline domestic route this November originates at Charlotte Douglas International Airport (CLT), a hub that it inherited from US Airways when the two carriers merged. The corridor in question serves Greenville (GSP), just 76 miles (122.3 km) away, with two daily round trips a day for most of the month using Airbus A319 and A320 aircraft.

However, even shorter than this is one of the routes operated under the American Eagle brand, namely the 67-mile (107.8 km) route from Milwaukee (MKE) to Chicago O’Hare (ORD). This corridor sees up to eight flights a day, primarily operated by Bombardier CRJ regional jets from SkyWest Airlines. O’Hare has been the site of an ongoing turf war between American and United, but remains important, as AA’s Ben Humphrey explains:

“O’Hare has always been a vital hub for American, connecting the Midwest to our global network and bringing travelers from across the world to Chicago for business and pleasure.”

Delta Air Lines

Moving onto Delta Air Lines, Cirium’s data shows that its shortest mainline route connects Cleveland (CLE) with Detroit (DTW). While typically the domain of its Delta Connection regional brand, this 95-mile (152.9 km) corridor has two outbound flights and one inbound sector scheduled to be operated by Delta’s mainline jets this November. Two of these three flights will use the Boeing 717-200, while one will use the 737-900.

When it comes to the carrier’s shortest regionally operated route, this is also an example of a corridor that originates at its Michigan hub at Detroit Metropolitan Wayne County Airport. Its destination is also in Michigan, and comes in the form of Lansing (LAN), which is located just 74 miles (119.1 km) away.

Delta Air Lines’ regional partners, which are Endeavor Air and SkyWest Airlines for this corridor, favor aircraft from the Bombardier CRJ family of regional jets on this route, which is served between one and three times a day. The models in question in this instance are the CRJ700 and the CRJ900.

United Airlines

Third and finally, we have United Airlines, whose shortest mainline route in November of 2025 originates at Denver International Airport (DEN). From here, the Star Alliance founding member uses Airbus A319 and A320 narrowbody twinjets to operate mainline flights on the 72-mile (115.9 km) domestic route to Colorado Springs (COS). These services operate twice a day for the most part, providing vital intra-Colorado connectivity.

As it happens, United’s regional ‘United Express’ also has a considerable presence on the route from Denver to Colorado Springs. This comes in the form of as many as 10 flights a day operated by SkyWest Airlines, although this isn’t the shortest domestic corridor served by its regional partners this month.

Indeed, that honor falls to the route from Chicago O’Hare to Milwaukee, which, on most days this month, will see eight United Express round trips operated by SkyWest Airlines and another two by Republic Airways. The latter solely flies Embraer E-Jets, while the former uses them alongside Bombardier CRJs.