With all the time we spend talking about youth sports, it’s interesting to look at some of the more common sporting events that you probably see just about every weekend in your area—the charity 5K or 10K that you’ll run into (or be detoured around) on Saturday mornings.

According to 2015 stats from Running USA, the number of recreational athletes completing road races declined for the second straight year in 2015. The reduction was by a more significant margin than in 2014, when finisher totals edged down one percent. For 2015, 17.1 million finishers were reported across all road race distances, a decrease of nine percent from the previous year.

Between 1990 and 2013, finisher totals skyrocketed from five million road race runners to more than 19 million. But there is one group that is experiencing its own running boom—women.

Women and girls, once an afterthought in the world of running, made up 57% of the 17 million U.S. race finishers last year, again according to Running USA.

And in part, you can thank Oprah.

In 1994 Oprah Winfrey completed the Marine Corps Marathon, accompanied by reporters and thousands of cheering fans along the route. All of a sudden, being a woman in a marathon was something cool and attainable—hey, if Oprah can do it, why can’t I?

At the time, men made up 68% of U.S. road race finishers. After Oprah’s marathon, and the beginning of a surge in female-themed running events, women started running—and by 2010 female finishers passed male finishers in this country, again according to Running USA.

Why the increase? A couple of reasons stand out: First, the gear is stylish and cool. You can look good in women’s running gear, whether you’re on the treadmill, on the street or on the couch. Nike estimates that sales of its women’s products will roughly double by 2010, according to a Wall Street Journal article.

Another reason: Running for a cause is a popular notion. In this year’s L.A. Marathon, women made up 46% of the runners but 59% of those who ran for charity. And a third reason that women have taken to running: It’s become a social activity. From Black Girls Run to Moms Run This Town and more, groups of women use running not just for exercise, but for a social experience. Whether it’s a physical training group or a virtual one that meets on Facebook or other social media, it’s a chance for women to talk about their accomplishments and more.

So cheer on the women who are giving running across the country a boost. And while you’re at it, if you’re looking for a fundraiser for your 501c3, a 5K is not a bad idea—running is more rewarding when you’re doing it for a charity.