The magic number for races seems to be 70. If you have a race with fewer than 70 entrants, race management can be done in less than 3 hours and for less than $10 (not per runner - TOTAL). You don't have parking problems, you don't have permits, you don't have awards.
In the 1970's, there were what were called popsicle races. Instead of race numbers being worn, runners received something with their place number on it as they crossed the finish (tongue depressors were actually more common than popsicle sticks; I preferred decks of playing cards - anything waterproof works). Ideally, you'd have 3 people working the race: one would start the runners and their stopwatch and then read the times out at the finish, one would write down the times on a clipboard and one would hand out the numbers. After all the runners came in, the runners would then turn in their numbers so that they could have their names attached to their times. This method works for up to 70 runners. Complete results could be quickly posted on the internet or emailed to participants.
If you have 7-10 teams of 7-10 members, each team is responsible for one race. This way, the runners take ownership of the races and try to put on the best event they can and they don't complain much if something goes wrong at a race (they learn not to make the same mistake).
Where you train is where you race. Think about it: you already have a favorite place to train and you don't think that the number of crossings of busy streets is too great, you think the restroom facilities and water availability is sufficient and you probably know exactly how long your course is. You don't need an accurately measured course, much less a certified one, but if you want, you can run over your course with a GPS and get a distance that's as close as anyone needs it to be. If one chooses a good course, it's possible to post or send entrants a map and a detailed course description and it isn't necessary to mark the course on the day of the race. If a course does have to be marked, chalk is best on pavement (poured chalk works on dirt and grass), assuming it doesn't rain; rain may require signage.
Races under 7 miles can be held on consecutive weeks. [It's difficult to get people to travel to races under 3 miles, unless there's something very special about the race.] Races between 7 miles and a half-marathon require a week off between them; these also may need a water stop (particularly in hot weather), so the best plan is a looped course that has the aid at the start/finish. Races should be scheduled around major races that others have scheduled in the area, to avoid conflicts and one should check to make sure that there aren't other events taking place at the same spot at the same time - not knowing that one's crossing a parade route, for example, is a disaster in the making. Races much over 13 miles become problematic and time-consuming and are best avoided for series like this.
With 7-10 races, this gives a racing season of 3-4 months, which is short enough to keep people engaged and allows runners to do other races at other times of the year.
A common question is how one can compare performances at one race with that at another. If the same people are running, it is a matter of place, rather than time. [Racing isn't about time! If you're running with a friend, you might say, "Race you to that sign at the top of the hill," and time would be irrelevant.] Using the same races each year allows people to compare their times from year to year.
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