Last year, demand for domestic flights departing or arriving at St. Louis Lambert Airport (as measured by O&D Passengers) was it's highest since the year Kurt Warner led the Greatest Show on Turf to a SuperBowl championship. In 2024, STL had 10.54M Domestic Origin & Destination Passengers (people not traveling internationally who start or end their journey in STL as opposed to connecting through the airport). That total was just a shade below the all time high of 10.80M in 2000.

While that is good that the airport was near its highest ever demand, the downside is that STL's demand has stayed mostly the same for 25 years while many other airport's demand has grown. STL's O&D has been between 9.0M and 10.8M in each of the past 25 years. To put it into perspective, in 1994 STL had the 21st highest domestic O&D of all airport's in the US. Miami was one spot ahead of it at 20th and Minneapolis was one behind at 22nd. Since then, MIA's O&D Passengers has gone up 110% (to 19.6M in 2024) and MSP's has increased 129% (to 20.6M), meanwhile STL is up only 14% over the same time period. Now Those two locations have major hubs and with etxra hub routes will come some induced O&D demand, but it's still quite a large gap to have grown over 30 years. I previously have written about STL's O&D (using data through 2018) and how the US's top airport's O&D has changed in the past decades. Today I'll provide some updates on numbers through 2024 as well as call out some comparisons and trends that I did not previously touch on.

Comparing STL to some of it's geographic and size peer airports, they do appear to have fared a bit better. Including STL, there are 11 airports that had between 5 and 20M O&D passengers in 2024 that I classified as in or near the Midwest. While their have been some with big growth (like BNA), many others followed a similar stagnation to STL. Below I show the O&D for each of these 11 airports since 1993 (with STL highlighted in blue). STL fares reasonably well against these peers, but it's almost shocking how flat the trend is (excluding the COVID spike). Every other airport in the chart had greater variation in their numbers (good and bad) than STL.

Maybe the closest comparisons are the other airports that were dehubbed in the past 25 years along with STL. Looking at CLE, CVG, PIT, St. Louis has always had more O&D than those previous hubs. In their peak year between 2000 and 2010, CLE's demand was 8.2M, PIT's 7.4M, and CVG's 5.5M. After flight reductions, those dropped to 5.1M (-37%), 3.3M (-41%), and 6.5M (-11%), respectively, while STL's low point was 9.1M (-16%). PIT had particular interesting numbers as it's O&D continued to grow for several year despite flight reduction from US Air beginning around 2004. While STL did not see some of the steep drop offs elsewhere, it also did not bounce back as quickly after bottoming out in demand. CLE, CVG, and PIT all hit new record highs for O&D in 2024, while STL was close, it's not there yet

STL fared better in the immediate aftermath of of flight reductions and showed the airport could maintain it's strong O&D, but it has failed to grow substantially since then, specifically in the last 10 years. It did have some momentum in the 5 years preceding the pandemic, growing O&D back up over 10M for the first time in over 15 years, but many other airports grew faster during that time period. By ranking the airports based on O&D, we can see how STL has changed relative to other US airports. Below I plot the top 50 airports in the US based on yearly domestic O&D Passengers with STL again highlighted in blue (and the other comp midwest airports in light gold. A previous blog post showed a chart similar to the one below showing ranking up to 2018. In that post St. Louis had been on a downward trend, dropping 11 spots in the 8 years leading up to 2018. But with 6 additional years of data, STL has actually gained one back and has stayed at the 37th rank in 2023 and 2024.

Putting the O&D totals along with the ranking helps to contextualize the numbers. Overall I think you can roughly break out different trends happening every 6 years or so.

• 1993-2000: Last Hurrah of TWA - we see total O&D rising slowly over these years to hit its all time peak in 2000, but even as this happens STL's ranking drops from a peak of 20th, down to 26th in 2000. Other hubs (eg. BWI,SLC, IAD) and a rising amount of leisure spots (FLL, PDX) O&D growing faster.
• 2000-2006: STL survives the dehub - total O&D see small declines, but as Southwest adds routes, the drop is not as bad as other airports that have lost hub status. Additionally, O&D around the country stagnates some post 9/11 and STL stays at 29th ranking through 2026
• 2006-2012: Maintaining Rank - total O&D continues to see small declines post financial crisis, but again other airports fare much worse and St. Louis actually climbs in the rankings back to 28th by 2012.
• 2012-2018: Missing the Rebound - STL's O&D total grow back over 10M, but during this period many other locations are seeing large upticks, outpacing STL. While some airports see double digit annual growth, STL stays in the low single digits. Ranking fall to an all time low at 38th
• 2018-2024: Bouncing Back Better - COVID cause a several year gap in everyone's growth, but again STL weathered the downturn as well as most places and by 2024 was back above its immediate pre-COVID peak. It's ranking follows suit and ticks up to 37th.

Looking at the periods outlined above, St.Louis has some times of (modest) growth and some (again modest) contraction in raw O&D numbers. Overall, it seems to handle the down periods (post 9/11, financial crisis, COVID) well, but during the periods of growth, it often finds itself at a lower level compared to other airports. The periods when it has seen the largest drops in its O&D ranking relative to all airports has oddly been during periods when its O&D has increased. This trend is a bit concerning because I do not think it's a great long term strategy to hope for more downturns. All jokes aside, ideally STL can figure out a way to grow at a faster pace during healthy times because that is the key to really growing the raw O&D totals.

While I speak of "creating growth" as something simple, it is obviously not something formulaic an airport can just start doing. O&D demand is in theory driven by the growth and travel needs of the entire surrounding metropolitan area and its businesses. If a population is clamoring (and willing to pay) to travel to more destinations, some airline will usually find a way to add service (Lufthansa taking ages to go 5 days on its Frankfurt route notwithstanding). Maybe in a future post, I'll look into total O&D demand relative to a metropolitan area's population or GDP, to see if places are over or underserved. But until then, hopefully STL can keep building its O&D and hit a new all time peak soon.

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All data for this post was sources from DB1B datatsets available via the Bureau of Transportation Statistics.