I wrote some of this and also put together the basis for the Tableau visualisation at the bottom.
What I found quite interesting was how the larger marathons seemed to spread by continent. They were being founded in the US sporadically for the first half of the twentieth century and then suddenly there was a rush in the late 70s and early 80s in Europe. A similar thing happened later on for Asia.
The sample size is not that big because obviously there are not that many marathons with over 10,000 people running but it’s still quite a nice thing to watch on the map. I could get a Tableau animation in worksheet view but not in dashboard view. Anybody else have this problem?