The presidential debate between former President Donald Trump and Democrat Vice President Kamala Harris attracted 57.5 million viewers across seven TV networks, according to preliminary Nielsen data released Wednesday.
Tuesday night's event was the first time the candidates in the Nov. 5 presidential election met face-to-face.
The viewing figure tops the roughly 51 million people who watched Trump debate President Joe Biden in June.
It does not capture the full extent of online viewing, which has grown in popularity as traditional TV audiences decline. Nor does it reflect viewers who watched the debate in bars and restaurants. Final audience data that includes those viewers will be available later Wednesday.
The record TV audience for a presidential debate occurred in 2016, when 84 million people tuned in to watch Democrat Hillary Clinton debate Trump.