Nielsen estimates that 31 million viewers watched TV coverage of President Donald Trump's inauguration.
That's better than Barack Obama's second inauguration but well short of his first.
The most-watched inauguration since 1969 was President Ronald Reagan's first oath-taking in 1981, which was seen by 41.8 million people.
The audience total measures continuous coverage by 12 broadcast and cable networks.
In 2013, 20.6 million viewed Obama's second inauguration. His first inauguration, in 2009, was seen by 37.8 million people.
For Trump's big day, NBC was the most-watched broadcast network with 5.8 million viewers, followed by ABC with 4.9 million and CBS with4.6 million.
On cable, Fox News Channel was far ahead, with 8.43 million viewers. CNN had 2.46 million and MSNBC had 1.35 million.