Southwest is one of several airlines squeezing seats closer together in order to pack in more passengers, create rows with extra legroom for people willing to pay more, or both. It has started adding six more seats to its planes, losing an inch of room between seats in the process. WestJet, out of Canada, is whacking several inches of space to make room for a section of higher-fare seats with extra legroom.

Even JetBlue Airways, which has long boasted the most legroom in the industry, announced earlier this month that it had removed an inch of legroom in the rear 11 rows of its Embraer E190 aircraft to accommodate expanded legroom in new, higher-priced rows.