Updated with additional information from Twitter and Facebook.

Monday night's debate between Hillary Clinton and Donald Trump may not have ultimately changed the minds of many voters, but it provided no end of fodder for Twitter (TWTR) - Get Report , Facebook (FB) - Get Report and other social media networks.

Twitter said the event was the most tweeted-about debate ever, but did not immediately have a tally.

Facebook reported that 18.6 million people in the U.S. made 73.8 million posts, comments, shares and likes about the debate. While the social media site does not have comparative data from the first election in 2012, the first Republican primary debate in August of last year scored 20 million likes, posts, comments and shares from 20 million people.

Taxes topped the list of issues for Facebook users, according to the company, followed by ISIS, race, the economy and crime.

On Twitter, however, the economy was the most tweeted-about topic, followed by foreign affairs, energy, terrorism and guns. The most tweeted-about comment was Trump's assertion that he has a good temperament.

The most retweeted post was this one from 2012 from Trump himself.

The Twitter conversation overall also skewed more heavily towards Trump.

However, more participants identified with Clinton early in the debate.

There was also a call for fact checking.

Facebook (FB) - Get Report reported Monday night that its greatest activity in the first half of the debate came when Trump said, "She tells you how to fight ISIS on her website. I don't think Gen. Douglas MacArthur would like that too much."

In the second half, the most Facebook posting and commenting occurred when Trump boasted that "My strongest asset is my temperament."

While Comcast's (CMCSA) - Get Report NBC took the the lead by broadcasting and moderating Monday's highly-anticipated presidential debate, Facebook, Twitter, Alphabet's (GOOGL) - Get Report Google, Snapchat and other internet companies played an increasingly large role.

Facebook was the official social media sponsor for the opening Presidential debate, which NBC Nightly News anchor Lester Holt moderated. Holt and other moderators of this cycle's debates received data about searches and postings from Facebook and Google to help gin up questions, according to Civic Hall Labs.

Twitter and Bloomberg livestreamed the debates at debates.twitter.com, via Twitter Moments and at the @bpolitics handle.

Previous data from Twitter told many of the high and low points of the campaign. According to the micro-blogging service, tweets about Hillary Clinton peaked in late July at the Democratic National Convention, while the FBI press conference on her email use in early July and reports about her health in September also reached high levels.

Trump's highest number of tweets were at the Republican National Convention in July and when Romney denounced the Republican nominee in March.

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During the first debate between President Obama and Mitt Romney in 2012, Twitter users sent 10 million tweets. 

Google's YouTube streamed Monday night's debate for PBS, The Washington Post, Telemundo and Fox News, among others.

And popular messaging platformSnapchat kept tabs on the Presidential showdown through its Live Story feature.

Deep Root Analytics forecasted that 81 million to 94 million viewers would watch the debates on TV, and that 27% of all registered voters would follow the showdown between Clinton and Trump on social media.

Among those watching the entire debate on TV, Deep Root projected, 38% would also follow the event on social media, up from 11% from the presidential debates in 2012.