The combined audience for the 13 networks that aired Monday's event topped that waterline for presidential debates.
It drove traffic online as well, with 17.1 million Twitter interactions related to the presidential debate from 2.7 million people in the U.S., Nielsen said.
The last round of debates, between Mitt Romney and Barack Obama, topped out at 67.2 million viewers.
Other notable draws were the 1992 debates with Bill Clinton, George H.W. Bush and Ross Perot, which drew a peak audience of nearly 70 million viewers.
Monday's debate audience put the presidential race's signature event in a league with the most-watched event on television.
With more than 114 million viewers, Super Bowl XLIX's matchup last year between the New England Patriots and Seattle Seahawks was the most watched event in U.S. television history, according to Nielsen data.