Over 73 million people watched the first debate on TV

More than 73.1 million people watched the first presidential debate on television on Tuesday night, according to Nielsen ratings.

Why it matters: While that's a sizable audience for any American TV program, it's down more than 13% from the record number of TV viewers who tuned in for the first debate of the 2016 election. The chaotic nature of the debate and the overall uncertainty around this year's election may have pushed some viewers away.

• The ratings drop could also reflect the fact that more people are streaming compared to 2016. About 15% fewer American households have pay-TV now than did in 2016.
• There's no way of measuring exactly how many people streamed the debate or watched clips of it on social media, but millions more Americans presumably tuned in online.

Nielsen ratings used to only measure traditional TV viewership. This year, out-of-home viewing, viewing in places like bars and restaurants, and connected TV (CTV) viewership on platforms like Sling TV were also included.

• Viewership from CTVs can comprise as much as 11% for televised political events, Nielsen says. But Nielsen still doesn't measure streaming on platforms like YouTube, Facebook or Twitter.

Details: As was true of this year's conventions, viewership on broadcast networks like ABC, NBC, FOX and CBS was down substantially this year compared to cable.

• Fox News, for example, said the debate drew the highest number of viewers for a debate in its history. Fox News drew the overall highest number of viewers this year, followed by ABC, NBC, CNN, MSNBC, CBS and FOX (the broadcast network).
• Broadly speaking, broadcast viewership has been down during the fall season due to the pandemic. Broadcast news networks tend to attract fewer partisan viewers than their cable counterparts.

Between the lines: Despite the fact that viewership was down, most people who did tune in were glued to their screens.

• Most viewers (90%) watched more than six minutes of the 90-minute debate, and just over half (54%) watched 56+ minutes of it, with the average person watching for 49 minutes, according to an analysis from MiQ, a marketing intelligence company,
• Viewership peaked between 9:30pm and 9:45pm ET, during questions about showing up to rallies and the economy.

The big picture: Despite drawing fewer TV viewers this cycle than last, the first debate drew a sizable audience.

• At least twice as many viewers tuned into the debate compared to any night during the Democratic or Republican conventions. Aside from the Super Bowl, the debate was likely one of the most-watched television events in America this year.
• Up until Tuesday's event, first debate viewership had been rising for the past three presidential cycles. The first debate between Hillary Clinton and Donald Trump drew a record 84 million viewers, the highest-rated first debate in history.
• Tuesday was the third most-watched first debate since 1976.

Our thought bubble: For President Trump, a former reality TV star, TV ratings are a proxy for popularity, so it's no surprise that the president tweeted approval of the ratings Wednesday afternoon.

• "HIGHEST CABLE TELEVISION RATINGS OF ALL TIME. SECOND HIGHEST OVERALL TELEVISION RATINGS OF ALL TIME. Some day these Fake Media Companies are going to miss me, very badly!!!" he tweeted.

What's next: The event, which was described as a "dumpster fire" by some pundits, has sparked a debate over how the remaining debates should be conducted. The Commission on Presidential Debates on Wednesday said it wants "additional structure" for the remaining debates, which are on the following dates:

• Oct. 7: Vice presidential debate
• Oct. 15: Second presidential debate
• Oct. 22: Third presidential debate

Go deeper: Chris Wallace struggles to control debate from Trump interruptions