Answer: British Olympic Planners

Modern marathon races are a very specific and seemingly arbitrary length: 26.219 miles. The particular distance doesn’t translate well into anything. It’s not a round number. The 0.219 extra hanging on the end there doesn’t come from a conversion from kilometers (and, in fact, converting the marathon length into kilometers leaves just as big a mess of the numeric portion to the right-of-the-decimal, as 26.219 miles is 42.195 kilometers). So where did it come from?

You can thank British Olympic planners. The distance seems completely arbitrary to us today, but when viewed through the context of planning the 1908 Olympic events, the distance makes a surprising amount of sense. The distance of 26.219 miles (or, more specifically, 26 miles and 385 yards) was the distance from Windsor Castle to the Olympic Stadium in West London at Shepherd’s Bush. The specific yardage at the end was the result of the runners entering the stadium opposite the royal box and running clockwise around the stadium to finish in front of it.

The drama surrounding the race (by the end, the runners were very exhausted and the end of the race was quite a sight to behold) coupled with the attention both the Queen and the international press lavished on the contestants, in turn, made marathon running an international craze. Over a hundred years later, runners around the world are still racing the distance—be it on the streets of Paris or Los Angeles—between Windsor Castle and the royal box at the old Olympic grounds.