CNN's audience Tuesday night was the largest ever for a Democratic TV debate.
According to Nielsen Fast National ratings, the telecast was seen by an average audience of 15.3 million viewers.
While that is only about 62 percent of the 25 million that watched the first GOP debate on Fox this year, it nevertheless topped the previous high for a Democratic debate on cable TV -- CNN's 2008 Los Angeles telecast, which averaged 8.3 million viewers.
It also topped the most watched Democratic debate in network TV history -- ABC's 2008 Philadelphia Democratic debate that averaged 10.7 million viewers.
The debate was also a winner in the key demographic 25-54, where it averaged 4.8 million -- the all-time high for a Democratic debate.
If nothing else, these numbers clearly show the huge tune-in for politics this year is about more than just Donald Trump.
More from CNN on its success in social and mobile media :
CNN live streamed the debate to CNN.com, its mobile apps and Apple TV, setting an all-time record for peak concurrent streams of a live news event. At 10:20pm, usage peaked at 980,000 concurrent streams, topping the 921,000 peak concurrent streams CNN saw of its GOP debate at Reagan Library. For comparison, it's estimated that NBC pulled in 1.3 million peak concurrent streams of the Super Bowl earlier this year.
In addition, CNN's Democratic debate day earned 4.3 million total live streams (web, app, and Apple TV) and more than 13 million total video starts.