The New York Times:
The first of three presidential debates between President Obama and Mitt Romney reached more than 70 million viewers on Wednesday night.
Nielsen, a television measurement company, said 67.2 million viewers watched on television at home — the highest number for a first debate since 1980. That year, 80.6 million watched the only debate between President Jimmy Carter and the Republican presidential candidate, Ronald Reagan.
A few second- and third-round presidential debates since then have attracted more than 67 million viewers, including the second debate of the 1992 cycle. Nonetheless, Wednesday’s totals were surprisingly high by almost any standard.
About 52.4 million viewers tuned into the first debate in 2008, according to Nielsen, though that debate was held on a Friday night, typically a lower-rated night of the week. About 62.5 million viewers tuned into the first debate in 2004, which similarly featured an incumbent president and a challenger.
(...) Of the 11 traditional channels that televised the debate and subscribed to Nielsen ratings, ABC was the most-watched, with almost 11.3 million viewers during the commercial-free debate, Nielsen said. NBC and CBS were close behind, with 11.1 million for NBC and 10.6 million for CBS.
Fox News Channel was as big as any broadcaster, with about 10.4 million viewers during the debate (up from 8.2 million in 2008 and 9.6 million in 2004). The Fox broadcast network attracted about 6.9 million; CNN, 6 million; and MSNBC, 4.7 million. (Fox News, MSNBC and CNN all skew toward older viewers, but interestingly, CNN had a surge of 18- to 34-year-old viewers for the debate — nearly 1.5 million, versus 882,000 for Fox News and 772,000 for MSNBC.)
More than 2.6 million Spanish-language viewers watched on Univision, and another 248,000 watched on Telemundo, according to Nielsen. (Telemundo showed the debate on a tape delay.) The lowest-rated of all the channels with the face-off was Current TV, Al Gore’s fledgling liberal cable channel, which had about 100,000 viewers.