Would you walk a mile for an airline flight?

You may. Airport terminals are getting longer for bigger planes, more gates and extra retail space. Connecting flights are sometimes located farther away because airlines have spread operations over more terminals. In Philadelphia, that means a literal walk over the county line. And in Chicago, Newark, N.J., and Orlando, Fla., moving walkways have been removed recently to make room for seats, bars and restaurants.

Several airports now report their longest potential walks stretch more than a mile, with some much longer. Trams, buses, carts and wheelchairs can shorten those hikes.

“The bigger airports are getting bigger. The medium airports are getting bigger. The aircraft are getting bigger,” says Wilson Rayfield, head of the aviation practice at Gresham, Smith and Partners, a Nashville, Tenn., architecture firm that has worked at airports in Atlanta, Denver, San Francisco and others. As airlines have moved to larger planes, gates have been spaced out more.

Mr. Rayfield says walking distances grow because airports extend concourses to add gates or build new concourses that are more remote. Walking between Atlanta’s new international terminal and domestic terminal check-in is 1.67 miles, for example. There’s a train, but the walk has “some of our most interesting art displays,” an airport spokesman says.