Four More Examples of Sold Out Marathons

Feature image by Nils Huenerfuerst on Wikimedia Commons - CC BY 4.0.

This summer, two popular marathons sold out far earlier than is typical: Philly and Twin Cities. In both cases, I saw someone ask – perplexed – if these races were really on pace to sell out. And days later, they were both full.

I did some good old fashioned historical research, and it turns out that in previous years, Philly hasn’t sold out until the fall. In recent years, Twin Cities typically had availability through the fall as well. These are both examples of how increased participation among runners is increasing demand for races – leading to bigger fields and earlier sell outs.

That got me wondering about how prevalent of a phenomena this is. I’m still in the process of gathering some data to paint the bigger picture, but in the meantime I wanted to share some datapoints from four additional races: Detroit, Colorado, Colfax, and Miami.

The Detroit Free Press International Marathon

The Detroit Marathon is one of the oldest in the country. It was originally founded in 1963 as the Detroit Motor City Marathon, and it took place on Thanksgiving Day. The race was taken over by the Detroit Free Press in 1978, and it was rebranded the Detroit Free Press International Marathon.

It has always been popular, in part because the race’s unique course travels through two countries. You cross over the Ambassador Bridge into Canada and return through the Detroit-Windsor Tunnel. But I did not think this was a race that typically sold out months ahead of time. While I was compiling a list of popular fall marathons – back in March – I was surprised to see that Detroit had already sold out.

On March 20, 2025, CBC reported that the race had already sold out. An interesting anecdote included in that article is that Canadian participation at the race was on the rise, despite the current political climate. I looked back through their Facebook page, and they announced the sell out two weeks earlier, on March 6.

In 2024, the marathon reported record participation and noted that the race sold out for the first time. Both the marathon and the half marathon sold out. The CBC reported on July 26 that the race had sold out the previous week. So the sell out took place over the summer, about three months prior to race day.

In 2023, the marathon reported that participation numbers had returned to pre-COVID rates. They expected around 24,000 runners (across all races), which was not far off from the 26,000 that would participate in the next two years. But on September 13 – the registration deadline for international races – they were still advertising open spots for the marathon on Facebook. The marathon relay had, however, sold out.

So just two years ago, the race didn’t sell out, and the reporting in 2024 suggests that it had not historically sold out prior to COVID, either. Since then, the race sold out in July last year and even earlier (March) this year.

The Colorado Marathon

When I sent out the Twin Cities story in my newsletter, I asked for some other examples of races that were selling out. And someone sent back this tip: the Colorado Marathon. Registration for the 2026 race just opened on July 1, and the organizers made it clear that the race sold out quickly in the three previous years.

How quickly?

In 2023, the Coloradoan reported that the marathon sold out on the Wednesday prior to the race. The next year, 2024, the Coloradoan reported that the marathon sold out on the Tuesday prior to the race. So not exactly “quickly” – but definitely sold out.

This year, though, the race did close much earlier. On February 27 – more than two months before the May race – they posted on Facebook that the marathon and the half marathon were sold out.

I couldn’t find any evidence that the race had sold out pre-COVID. In 2019, they were still advertising available spots on Facebook as late as April 13, and an archived version of the race website from May 2 suggested that registration was available right up until the deadline.

Note that the Colorado Marathon is a downhill race – but it’s net drop is low enough that it won’t be penalized with the upcoming Boston Marathon rules changes. That could lead to even more demand going into 2026.

The Denver Colfax Marathon

When I was searching for news about the Colorado Marathon, another race kept popping up in the results – the Denver Colfax Marathon. This is another Colorado race, taking place just weeks after the Fort Collins race.

In 2023, the local news reported that the race sold out for the first time, about a week before race day.

The next year, the Denver Post reported that the race had made some changes to accommodate more runners. They changed both the marathon and half marathon courses so they could increase the field size. As a result, the race marathon didn’t sell out. But local news reported that the half marathon and ten mile did sell out, and the total number of runners across the race weekend had increased by about 20%.

The following year, the half marathon and marathon relay both sold out. Although the marathon itself still had available spots, there was “little capacity” left, and the combined race weekend had a record number of registrants.

So in this case, some changes by the organizers prevented future – and earlier – sell outs. But that was a result of a significant increase in field size. In 2023, the marathon had 1,629 finishers. That jumped to 2,233 in 2024 and 2,281 in 2025.

If interest continues to increase – and if the nearby Colorado Marathon sells out more quickly – this race could end up selling out again in 2026.

The Miami Marathon

The final example for today – the Miami Marathon.

The 2025 Marathon sold out early. According to the Miami Herald, the race – which typically takes place at the end of January or beginning of February – had sold out on August 29. That’s about five months out.

In 2024, the Miami Herald reported that the race had sold out in mid-September. A search through the marathon’s Facebook feed yielded an announcement that the race was sold out on September 15. So early – but not as early as this year.

In 2023, the Miami Herald reported that the race increased capacity across the entire weekend of races from 15,000 to 18,000. Despite that significant increase, the marathon sold out on October 20.

And if you turn back the clock all the way to 2022, the race sold out in November. So about two months prior to race day – but much later than in more recent years.

Way back in 2014, a CBS news report included a comment from the general manager that there was a sold out crowd of 25,000 participants (across all races). But a 2017 news story a 2019 Miami Herald article each indicated that last minute registration would still be available at the expo. So it’s unclear just how often the race sold out prior to COVID, but there were definitely years where it did not.

Just yesterday – August 7 – the Miami Marathon posted on Facebook that it is “filling up fast” and “time is running out.” So it looks like things are on pace this year to be similar to last year, with a late August or early September sell out. If you Miami is on your to do list, I wouldn’t wait much longer before pulling the trigger.

What Other Races Are Selling Out?

I’m sure there are some other examples of races that are starting to sell out – or that are selling out earlier. It makes sense, given the general surge in marathon participation. But I’m curious about just how prevalent the phenomena is.