Thursday’s Republican primary debate was the most-watched such event in the history of American politics. With 24 million viewers, it was no Super Bowl, but the fact that 16% of Americans with TV sets tuned in is a huge improvement from the 5% who did so for the Republican debates in 2012 and 2011.

Part of the jump in numbers can surely be attributed to the increase in engagement by millennials. And a big reason for that increased engagement is the heavy involvement of the photo-sharing app Snapchat, suggests Kerry Flynn of the International Business Times.

Snapchat lets users create and contribute to “Stories” — live feeds of happenings in cities, at large events, or on special occasions around the country (e.g. July 4th celebrations). For the GOP debate, Snapchat created a story called “First GOP Debate.” Thursday’s Story consisted of photos and video clips from the debate, going live two hours before the debate. Watching the Story, Snapchat users could see behind-the-scenes views of the live event, along with candidates’ answers to questions from the media. There was also commentary from Snapchat’s Head of News, ex-CNNer Peter Hamby.

Politicians, including some of the Republicans on the stage Thursday night, have come to realize that Snapchat is one of the best ways to reach millennials, the IBT’s Flynn pointed out in a separate behind-the-scenes story. According to BI Intelligence, more than 70% of Snapchat’s users are millennials, by far the largest percentage among social network sites (Facebook’s millennials comprise 16% of its users). If Snapchat has 100 million active users, as CEO Evan Spiegel claims, that means 71 million millennials are using Snapchat regularly.

According to a survey conducted by Fusion, 77% of Americans between the ages of 18 and 34 say they’re “very likely” to vote in the 2016 election. Voters between the ages of 18-34 made up about 19% of the electorate in 2012, according to Pew Research Center, up from 18% in 2008. Multiple studies have shown young voters propelled President Barack Obama to his two electoral victories, especially in 2012 — and that was with only half of the millennial electorate showing up. In other words, the millennial vote matters. A lot.

If Thursday night was any indication, we’ll be seeing a lot more of Snapchat in the future as the primaries and, later, general election get into full swing.

Editor’s note: This story has been updated throughout to address issues of similarity to its source material.