President Trump’s first State of the Union address drew an audience of 45.6 million, about two million fewer than the number who watched his speech to a joint session of Congress a year ago.
The viewership figure, tallied by Nielsen from the broadcast networks and cable channels that aired the 80-minute address on Tuesday night, reflects Mr. Trump’s preferred manner of watching television: the old-fashioned way, on a TV set, in real time. It does not include streaming data.
The television audience was also smaller than the one for President Barack Obama’s first State of the Union address in 2010, which had 48 million viewers.
Mr. Trump’s joint session speech last year drew 48 million viewers, according to Nielsen, about four million fewer than the 52 million who watched Mr. Obama’s joint session speech in 2009. The comparison, though, is complicated by the fact that more people stream these days than they did even five years ago.
Fox News won the night, with an audience of 11.5 million.
The leading broadcast networks were CBS and NBC, each with an audience of roughly seven million for the president’s speech. Both benefited from highly rated lead-ins: CBS aired an hourlong special on Super Bowl commercials, and NBC turned to its hit new game show centered on Ellen DeGeneres, “Ellen’s Game of Games.”
The speech was also carried on several cable networks, including MSNBC and CNN, as well as PBS and the Spanish-language channels Univision and Telemundo.
With Mr. Trump speaking considerably more slowly than his predecessors, his State of the Union address was the third longest in the last 50 years.
Digital viewing is difficult to measure because statistics are not compiled by a third-party service, like Nielsen, that is regarded as an industry standard. CNN said that it had 1.7 million video starts on its website and across its apps during Mr. Trump’s address, and that viewership peaked a little before 10 p.m. with 320,000 concurrent users.
Coverage on Tuesday included Megyn Kelly’s debut as a prime-time analyst on NBC and the first night for Chris Christie, the former governor of New Jersey, as an ABC pundit.
During a luncheon with news anchors on Tuesday, Mr. Trump predicted that his address would have a bigger audience than the Grammys. He got that one right: The Grammys had 19.8 million viewers on Sunday, a drop of 24 percent from last year.
In the late-night numbers, Stephen Colbert, who returned to a live format on Tuesday, easily had the highest household rating with a 2.9 share, dwarfing the 2.3 for “Jimmy Kimmel Live!” and 1.9 for Jimmy Fallon’s “The Tonight Show,” according to Nielsen.
Mr. Kimmel, whose main guest was Stormy Daniels, the pornographic actress who reportedly got a settlement to keep a sexual encounter with Mr. Trump quiet, had the highest rating among the advertiser-coveted 18-to-49-year-old demographic in the 25 leading markets.