More than 19 million people watched coverage of the Super Tuesday primary results on the top broadcast and cable news networks.
Fox News Channel led the way with 4.17 million viewers, the Nielsen company said on Wednesday.
But CNN scored a key victory by leading all of the networks among viewers ages 25-to-54, considered the key demographic for ad sales in news programming.
MSNBC had 3.82 million viewers for its coverage in prime time on Tuesday. NBC had 2.94 million, CNN had 2.8 million, ABC had 2.72 million and CBS had 2.64 million, Nielsen said.
The broadcast networks cast aside their entire prime-time entertainment lineups to show the results in 14 primary states, an increase in time and resources over what was spent on Super Tuesday four years ago.