Running USA, the group that compiled the statistics for half marathon runners, points out a few other fun facts about just how many people are running these races: 
 
 Since 2010, 13.1 miles has been the second most popular distance by finishers behind the 5K. Since 2000, the number of half-marathon finishers in this country has quadrupled (482,000 to 1,960,000) or an impressive increase of 307%. Those are huge numbers, and Scott Douglas and Dan Fuehrer at Runners World have more, charting the race's increasing popularity: 
 
 In 1990, there were an estimated 303,000 finishers. That total had more than doubled by 2004. This year's record total of 1.96 million means that, in just less than a quarter-century, there's been more than a six-fold increase in finishers. Last year, two million people finished the 13.1 mile race, and 61 percent of those runners were women. But the biggest races of all were overseas: 45,126 people finished a half marathon in Sweden last year, and 40,763 ran one in Great Britain.
– Female runners are making half-marathons the sport's most popular distance race, reports Runner's World. It takes note of new stats from Running USA showing that a record 1.95 million people finished a 13.1-mile race last year, which marks a 6% increase from the previous year and an astonishing six-fold rise since 1990. Of last year's finishers, 61% were women, up from 53% in 2004. "Runners, it seems, are divided between people committed to running for maybe 40 minutes and people ready to hoof it for more than two hours," observes Rose Eveleth at Smithsonian. "If you fall somewhere in between, well, maybe it’s about time you try for 13.1 miles. Everyone else is."