The first US presidential election debate between Hillary Clinton and Donald Trump drew a television audience of 84 million US viewers - a record for such an event.
The figure beat the 1980 record of 80.6m set by Ronald Reagan and Jimmy Carter's presidential debate, but fell short of the 100m viewers many pundits had predicted.
Monday's figure does not include millions of people watching the debate online - through Twitter, Facebook - or the countless others watching in pubs and bars.
YouTube reported nearly two million live concurrent streams of the debate on its platform.
Managing director at Dentsu Aegis Network, Michael Law, said: "Clearly the debate did really well last night."
NBC News, whose 'Nightly News' anchor Lester Holt chaired the debate, led the audience share with an estimated 18.2 million people tuning in. Early Nielsen data showed Fox News averaged 11.4 million viewers.
By comparison, NFL's annual Super Bowl showdown attracts a television audience more than 100m viewers, making it the largest US televised event.
Mr Trump and Mrs Clinton will take part in two more debates before the November 8 election.