That is the lowest showing since 2000, when President Clinton's speech averaged 31.5 million viewers.
Total viewership for the address, which aired live from 6 p.m. to 7:15 p.m. PST on 13 networks and tape delayed on Univision, was down slightly from last year's. The 2013 State of the Union was watched by about 33.5 million people.
Among cable outlets, the Fox News Channel beat its rivals, as usual, with 4.7 million viewers.
According to Nielsen SocialGuide, Americans sent out 2.1 million tweets about the address.
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