Southwest Airlines nudged aside American Airlines as the US carrier transporting the most passengers in 2016, according to the Department of Transportation (DOT).

A total of more than 151.7 million travellers flew on Southwest last year, up from 144.6 million in 2016. The 5 per cent increase in Southwest’s passenger volume propelled the airline ahead of American Airlines, whose enplanements fell 1.6 per cent between 2015 and 2016, to 144.2 million.

The 2015 American Airlines data included flights on merger partner US Airways, which has now been fully integrated into American’s operations.

Delta Air Lines posted a 3.2 per cent increase to remain in the number-three slot in passenger volume in 2016, with 143.1 million enplanements. United Airlines’ passenger volume rose 5 per cent year-over-year to top 100 million enplanements for the first time, allowing the airline to keep its hold on the fourth spot.

Other US airlines carried significantly fewer passengers than the top four carriers. JetBlue, for example, posted a 9 per cent increase in enplanements but still only carried a comparatively modest 38.2 million passengers.

SkyWest carried 31.2 million passengers, followed by Alaska Airlines (24.4 million), ExpressJet (22.2 million), Spirit (21 million), and Frontier (14.8 million). Of these, Spirit saw the biggest jump in passenger volume (19.1 per cent), while ExpressJet carried 14.7 per cent fewer passengers in 2016 than 2015.

American Airlines continued to be the top international airline serving the US, followed by United, Delta, JetBlue, British Airways, Lufthansa, WestJet, Air Canada, Virgin Atlantic, and Air France.