The third presidential debate between Hillary Clinton and Donald Trump drew an estimated television audience of 71.6 million.
That was lower than the audience for their first TV clash, but still the third-highest total ever recorded.
Their September meeting attracted an audience of 84 million, the largest in the history of US presidential debates.
The second debate was seen by 66.5 million people in the US, according to the Nielsen ratings agency.
The agency looked at the number of people who watched Wednesday’s debate on the four main US broadcast networks, as well as nine cable and public television channels.
It does not include those watching online, through social media or in bars and restaurants.
The debate, held in Las Vegas and moderated by Fox News’s Chris Wallace, was the final televised clash before the election on 8 November.
It was marked by Republican candidate Mr Trump refusing to commit to accepting the result of the election if his Democratic rival Mrs Clinton wins.
During the debate, Mr Trump was mentioned in 3.9 million tweets, while Mrs Clinton was mentioned in 1.9 million, Nielsen said.
Nielsen started collected TV viewership data in 1976.
In 1980, a debate between Jimmy Carter and Ronald Reagan, drew 80.6 million viewers – the only previous debate to match this year’s audiences.
Both debates undertaken by Bill Clinton when he was running for re-election in 1996 against Bob Dole were seen by just over 36 million people.