A record 84 million people tuned in to US. TV networks for the first presidential debate between Hillary Clinton and Donald Trump, a huge audience rarely seen on TV in the age of digital streaming and social media.
The estimated ratings figure from Nielsen included people watching the raucous face-off across 13 US cable and broadcast networks and public television station PBS.
The audience beat the 80.6 million record set by the Jimmy Carter-Ronald Reagan TV presidential debate in 1980 but fell short of the 100 million viewers some analysts had predicted for the event.
The TV figures did not include millions of people who watched the encounter online through Twitter, Facebook and other social media, including in large groups in bars and restaurants.
The National Football League's annual Super Bowl attracts more than 100 million viewers, making it the biggest US TV event.
Monday's debate was the first of three scheduled between Democrat Clinton and Republican Trump before the November 8 election. The other two are set for October 9 and 19.
CNN charged more than $US55,000 for 30-second ad spots as part of packages ranging from $US800,000 to $US1 million that included future debates and election night, according to a person with knowledge of the matter.
CBS charged between $US200,000 to $US225,000, according to another source.
"Clearly the debate did really well last night," said Michael Law, managing director of video investments at Dentsu Aegis Network.
