Educated Guesswork

Qualifying for prestige races (and why you won't get into Western States)

It's a common pattern: a new category of race starts up and initially it's not very popular, so you can just sign up. But the race can't accommodate an infinite number of participants, and if the sport starts to get popular, you can start to hit capacity limits. If they're not too bad you can just make things first come first served, but some really popular races—especially prestige ones like the Boston Marathon or the Hawaii Ironman—are in such demand that they would just fill up instantly. Obviously, this is one way to ration entry, but it's odd to choose based on how good someone is it hitting reload on their browser and unlike COVID vaccination, it's not just a simple matter of prioritization: some people will get in and some will not. Selecting the lucky few turns out to be a somewhat complicated problem, and the three endurance sports I'm most familiar with (road running, triathlon, and ultramarathons) have all developed different solutions.

At a high level, you can select people based on two basic criteria: merit and luck. Luck is theoretically easy: run a lottery (though in practice it's usually not that simple). Merit is more complicated, for reasons I'll get into below.

Road Racing #

Road race fields are typically very large (for instance, the 2019 Boston Marathon had 30000 runners), and so only the most famous and popular races need to do anything special beyond first come first served. If you're a popular race, though, you need to do something different. Boston is by far the most prestigious marathon in the US—and probably the world—and therefore is heavily in demand, even with this big a field size. They run a relatively straightforward system: each age bracket (mostly 5-years) has a qualifying time. If you hit the qualifying standard in any certified marathon then you are eligible to apply for Boston. A similar system is used for the US Olympic trials in marathon, where there is a qualifying time tuned to generate a field of a few hundred or so.[1]

This doesn't guarantee you entry, though: because more people hit the qualifying time than they can admit they also have a year-to-year adjustment to the qualifying time. For instance, if you are 41, your qualifying time in 2021 year was 3:10, but because of the small field size this year, they had an unusually high cut-off of 7:47, meaning you had to actually run 3:02:13 to be admitted. On the other hand, fewer people applied in 2022 and everyone with the official time got in. These times are fast, but are not out of reach for reasonably good runners. Many other prestige races use a combination of lotteries and time qualification.

Time-based qualification works well for road racing (or track) because times are relatively consistent and depend mostly on the flatness of the course and the weather (specifically, temperature and wind).[2] This means that most people have a fast (which is to say flat, low wind, cool) course available to them without too much effort, and so they have an opportunity to turn in a fast time. Indeed, it's quite common for races to advertise themselves as "flat[3] fast" and perfect for Boston Qualifying. Popular places to get the "BQ", as they say, are Tunnel Hill run in November in Illinois and California International Marathon (CIM) run in December in Sacramento[4]

Triathlon #

The Ironman race that everyone has as their goal is the Hawaii Ironman (aka "Kona"). By contrast to road racing, triathlon courses are somewhat less standardized and there are fewer races, so that means that there's a fair amount of variation in finish times; for instance the Ironman German course record is 7:41 and the Ironman Lanzarote record is 8:30. This, coupled with the relatively small number of entrants in Hawaii (about 2500) means that time criteria don't work well; there will be too much uncertainty at the margin.

Instead, the way this works is that Ironman Hawaii gives each race a fixed number of "slots", which is to say the number of athletes they can send to Kona. These slots are then allocated to each (typically five year) age bracket + gender (e.g., Male 25-29). If there are (say) 5 slots in a given age group, then they go to the top athletes in that age group. If a qualifying athlete doesn't want the slot—or already has one—then it "rolls down" to the next athlete. In some case, it's been known to happen that a slot will roll down off the end of the age group (especially in smaller age groups), and go to another age group. This structure creates a slightly odd dynamic: As with Boston qualifying, people gravitate to specific races, not on the basis of time but rather on the basis of which races appear to have "soft" winning times and thus be easier to qualify at. This can make a big difference if you are a solid but not elite age grouper who is just on the border of qualifying. I myself once flew to New Zealand to race because the previous year had had fairly slow winning times (I DNFed.)

Interestingly, the Hawaii Ironman used to run a lottery in which you could pay $50 to enter, but it appears that they have stopped doing that due to a settlement with the Federal government which treats it as gambling, I think because they charged you whether you got in or not.

Ultramarathons #

Ultras tend have even smaller field sizes than triathlons, both for logistical and historical reasons. The logistical reason is that it's hard to have a lot of people on single-track mountain trails—and of course it's hard on the trails. For instance, even the comparatively large Ultra-Trail de Mont Blanc (UTMB), the most prestigious European long distance ultra, has a field size of only around 2300 runners. The most prestigious North American ultra, Western States has a field size of under 400. The reason for this is that some of the event takes place in a wilderness region where races are technically forbidden, and so the race operates under a permit that keeps it to the size of the event before the wilderness was created. Other famous North American ultras like Hardrock 100 or Sonoma 50 also have relatively small field sizes.[5]

Unlike both road racing and triathlon, ultras manage the problem of oversubscription (at least for amateurs) almost entirely by luck and not by merit. As an example, Sonoma 50 runs a simple blind lottery for all admissions, including pros. The sole exception is the previous year's winner, who gets in without being in the lottery. It doesn't matter if you're back of the pack or going for the win, you're all in the same lottery. A more common structure is to have some kind of special affordance for professionals. It's not clear to me why this system has evolved, but I suspect it's something do with the generally less competitive ethos of trail running as well as the relative youth of the sport.

Western States #

Western States has a particularly ornate system, consisting of a set of about 100 "automatic entrants" plus a lottery with about 270 spots. The automatics are largely elites of various flavors, including:

  • The top 10 men and women in the previous year
  • 6 spots for elite athletes (mostly non-Americans) from the Ultra Trail World Tour.
  • The top two men and women from 6 different Golden Ticket races.[6]
  • Around 10 slots for race sponsors. For instance, Jim Walmsley famously won in 2020, turned down his automatic slot for 2021 because he didn't think he was going to race and then got in via his sponsor, shoe company Hoka.

If you're not good enough to run your way in or have a sponsor who will get you in (and you're not Gordy Ainsleigh who ran the course on foot back when it was just the Tevis Cup, Cowman AmooHa, or a few of the other notables), then it's the lottery for you.

The way the WS lottery works is that each year you have to "qualify" by finishing—occasionally within a certain time—one of a set of specified races. Unlike with Boston or the Hawaii Ironman, these qualifying requirements aren't set to pick out elite runners but just to weed out people who have no real chance of finishing Western. For instance, it's sufficient to finish Sean O'Brien 100K in under 16 hours. I'm not saying this is easy, but I finished under 13 hours and was well off the podium.

This all worked reasonably OK until the mid 2010s, at which point the number of applicants exceeded the number of slots by about a factor of about 10 and there were people who had been waiting to get in for 5 years. In 2015, they introduced a new system in which the number of lottery tickets doubled for every year you didn't get in. With a few small modifications[7], this is the system that exists now.

The obvious problem with this system is that it doesn't make any more slots; it just reallocates the probability of getting in from newer people to older people. This of course reduces the number of people who have been waiting a really long time, but at the cost of making it very unlikely for new people to get in. For instance, someone who entered the lottery for the first time in 2021 (for the 2022 race) had a 1.3% chance of getting in, and it's just going to get worse as long as more people want to run Western than can be accommodated via the lottery.

Hardrock 100 #

Hardrock 100 has an especially goofy system, with three separate lotteries:

Category Number of Tickets
Never finished 65
Veterans (five or more finishes) 25
Everyone else 55

When you add this up, you see that more than half of the slots are given to people who have already run Hardrock, so this has precisely the opposite bias as Western States uses (although they do use a similar doubling scheme for Never Finished, so at least it tends to reward waiting).

In practice, this has resulted in a terrible gender balance for Hardrock: because historically most of the people who have run Hardrock are men, this system just perpetuates that imbalance and will continue to do so as long as the number of first-time women doesn't massively increase. Starting in 2022, Hardrock's policy is to admit women in proportion to their fraction of the lottery pool. This won't actually bring gender balance because the number of men who enter is far greater, but it's potentially a step in the right direction. The High Lonesome 100 has gone even further and selects exactly as many women as men.


UTMB followed a similar path, starting with open entrance, then qualification, and finally a lottery, including a similar doubling scheme to Western States (the site suggests that they will no longer double after 2022). However they have now introduced a new change to the system in which you can collect "running stones" for participating in specific races (especially races owned by UTMB!) with each stone counting as another lottery entry. So, for instance, you get 9 stones for Thailand By UTMB. And the more races you do the more stones you collect. We should anticipate that in the future the majority of people will be selected via this mechanism, both because it's obviously a huge advantage and because the more people start using it the more of a disadvantage you are for just entering the ordinary lottery. This is, of course, good for business!

The Long-term #

As I mentioned above, as long as more people want to do these races than can be accommodated, any lottery system is sort of a temporary measure, because most people won't get to do the race ever. For instance, there were over 3000 first year applicants for the 2022 Western States. It would take over 10 years just to have all of them race, in which time another 30,000 or so people would be waiting. I think it's only now that people are starting to come to term with this and realize they are unlikely to ever get into Western States or Hardrock. Moreover, increasing the odds for people who have been waiting longer will actually have the paradoxical effect that wait times for people who get in continue to increase as the right hand side of the distribution is increasingly favored (the wait times of people who don't get in will of course always be infinite).

Western States Lottery Simulation

The graph above shows a simulation of 10 years of the Western States lottery under the (very conservative) assumption that the number of new entrants will continue to remain the same (in fact, it has been increasing for years). The area shows the distribution of wait times and the black line the mean number of years that selected runners have been in the lottery. As you can see, this means that the population of lottery winners will have been waiting longer and longer and will be getting correspondingly older. This is going to get especially weird in another 10-15 years as the pros are typically fairly young (under 40), so even more than usual you'll have two races, one for pros and one for amateurs.

The Bigger Picture #

At the end of the day there really isn't a great solution: there are just more people who want to do these races than can plausibly do so, so you need some way to select the lucky few. It seems like one could make an argument for either performance-based qualification (Boston and Kona) or lottery-based qualification. However, it seems to me that the doubling system used by Western States and the quota system used by Hardrock are long-term unstable, the former because it's just going to create an older and older population and the latter because it just seems unfair to favor people who have done the race 5 times over people who have never done it.

  1. This actually went a bit wrong in 2020, when they overshot the mark for women. The women's standard for entering the trials in the marathon was 2:45 and 511 women qualified. The standard has been dropped to 2:37 for 2024. I've seen arguments that a big field was good, but obviously USATF doesn't agree. It's certainly true that the logistics are hard because each runner gets to have their own individualized nutrition at aid stations, etc. ↩︎

  2. Temperature is actually a huge issue because running generates a lot of heat and your body has to work to get rid of it. The data is unsurprisingly pretty noisy, but the optimal temperature for running appears to be quite cold, somewhere around 5-10oC. ↩︎

  3. Courses can be net downhill but only by a little bit. ↩︎

  4. CIM also advertises "More porta-potties per runner at the start and along the course than any event CIM staff and board has ever seen!". This is more important than you might think. British marathon legend Paula Radcliffe famously had "bathroom issues" at the 2005 London Marathon and had to just go on the side of the course, going on to win anyway. ↩︎

  5. I actually got into the Sonoma lottery this year and plan to toe the line. ↩︎

  6. This works like Hawaii in that the slots roll down. ↩︎

  7. Specifically, they no longer require you to have applied in consecutive years. ↩︎

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