Ever wondered where Southwest’s passengers transit and where they go? Wonder no more!  Denver was its number-one airport for transit passengers last year, while Long Beach to Seattle was its top (transit) origin and destination. Islip to Chicago Midway, which was by far number-one in 2019, slipped down the table.

Southwest is renowned for being a point-to-point (P2P) airline and for saying it doesn’t have hubs. As a hub is a very specific thing, it is correct. Of course, this somewhat misses the point.

Transit passengers are crucial

While Southwest isn’t a hub-and-spoke airline because it isn't set up as one, connecting passengers – those transiting from one flight to another – are still enormously important. And since coronavirus began, transit passengers have become even more important to the airline.

In 2019, approximately 51 million of Southwest's 134 million passengers – or almost four in ten (38%) – connected, analyzing booking data obtained through OAG Traffic Analyzer suggests.

In 2020, in the midst of COVID, around 30 million of its total of 56 million passengers transited – some 55%. This illustrates the general view that since coronavirus began, airlines have focused more on their core hubs – or connection-orientated airports.

Denver was Southwest's leading airport for transit passengers. Photo: Vincenzo Pace | Simple Flying.

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Top-10 transit airports

Denver was Southwest's number-one airport for connecting passengers last year, as indicated below, with over four million estimated to have transited at the airport. Denver overtook Chicago Midway to become first, with Midway falling to third. The Colorado airport's share of connecting traffic rose to nearly 15% of the airline's total.

  1. Denver
  2. Baltimore
  3. Chicago Midway
  4. Dallas Love
  5. Las Vegas
  6. Houston Hobby
  7. Phoenix
  8. Nashville
  9. Atlanta
  10. St Louis

That's the thing about Southwest's top transit airports. They are also its top airports generally. Not only are they well-positioned across the country, but they're also in large and/or growing cities. This helps with the number of routes, P2P demand, higher frequencies, and therefore more connection opportunities. It's a virtuous circle.

Southwest's top-10 airports for transit passengers and – not coincidentally – also its largest airports generally. Image: GCMap.

Top-25 transit routes

While the overwhelming majority of Southwest's transit passengers were obviously domestic, getting on for two million still connected from abroad. These were primarily from Mexico to the US, but Puerto Rico – admittedly not a sovereign state – to the US had a decent chunk too.

Long Beach to Seattle was Southwest's number-one transit origin and destination (O&D) in COVID-hit 2020, as shown below, measured by total passengers. Around 55,000 connected between the pair, booking data shows, mainly over Oakland, Sacramento, and San Jose. This nicely indicates how most Southwest airports can be good for connections – and not just its top-10. This is also important for aircraft flow, passenger convenience, and competitiveness.

  1. Long Beach-Seattle
  2. Long Beach-Portland
  3. Chicago Midway-Reno
  4. Islip-Midway
  5. Baltimore-Phoenix
  6. Boston-Oakland
  7. Houston Hobby-Philadelphia
  8. Albuquerque-Oakland
  9. Los Angeles-San Antonio
  10. Midway-Oakland
  11. Albuquerque-Hobby
  12. El Paso-Los Angeles
  13. Los Angeles-Milwaukee
  14. Las Vegas-Raleigh Durham
  15. Fort Lauderdale-Phoenix
  16. Kansas City-San Diego
  17. Hobby-Oakland
  18. Los Angeles-Midway
  19. Midway-Phoenix
  20. Las Vegas-Orlando
  21. Los Angeles-St Louis
  22. Albuquerque-Orlando
  23. Oakland-Washington Dulles
  24. Phoenix-Tampa
  25. Albuquerque-San Diego
Midway to Reno was Southwest's third-largest transit market in 2020, with around 40,000 passengers. Nearly half connected in Las Vegas. The Nevada airport, along with Denver, Phoenix, Los Angeles, and San Diego, made up the vast majority of airports where passengers transited. Image: GCMap.

Long Beach to Seattle

Long Beach to Seattle is an interesting market. It had nearly half-a-million non-stop seats in 2011 with both Alaska Airlines and JetBlue. Alaska ceased the route in 2015, leaving JetBlue. By 2020, the market had reduced to less than 60,000 non-stop seats, and the route is now unserved following JetBlue pulling out of Long Beach.

Southwest Airlines has been flying additional fuel on its jets to airports affected by the shortage. Photo: Vincenzo Pace | Simple Flying.

A number of the 25 O&Ds listed above weren't in the top-25 in 2019 or, if they were, they had changed position. In 2019, Midway to Islip was top, with about 110,000 passengers.