GOP debate makes history with a record 24 million viewers tuned in
The event was also the highest rated telecast in the nearly 20 year history of the Fox News Channel, a spokeswoman said.
Of the 24 million viewers, 7.9 million were in the key advertising demographic of 25 to 54 year olds.
The ratings, which were delivered by Nielsen on Friday afternoon, shattered even the rosiest expectations for the beginning of debate season.
Earlier figures indicated that Fox had 16% of United States homes with TV sets tuned in while the debate was on between 9 p.m. and 11 p.m. Fox News usually has 1% or 2% of the household audience.
For the sake of comparison, the highest-rated Republican primary debates in 2011 and 2012 were watched by approximately 5% of households.
The Democratic primary debates in 2008 were bigger, but none of those ever topped 10%.
Interest in Donald Trump's candidacy almost certainly drove viewership on Thursday night.
The first Republican primary debate in 2011, also on Fox, was watched by 3.2 million people.
There was also a surge -- though much smaller surge -- in viewership for the undercard debate at 5 p.m.
The ratings are good news not only for Fox but for other media organizations that are sponsoring Republican debates. The "Trump show," as some have called it, seems likely to continue into the fall.
The next debates are set for September 16 (on CNN) and October 28 (on CNBC).
Fox had high expectations for Thursday's kick-off to debate season. Rival executives and campaign aides also predicted unusually high ratings for the event, thanks to curiosity about Trump and the controversy over the "top ten" candidate criteria.
But the overnight numbers seemed to surpass everyone's expectations.
There was speculation on Friday morning that it may go down in the record books as the highest-rated Fox News telecast ever.
On Thursday night there was immediate indication of the audience's interest: the debate dominated social chatter on Twitter and Facebook.
Fox made the debate available online to cable and satellite subscribers, but many users on Twitter said they had a tough time accessing it.
A Fox spokeswoman confirmed the problems and said "an unprecedented, overwhelming demand caused server issues in the debate live stream."
