Thursday night's vice presidential debate between Sarah Palin and Joe Biden was seen by 69.989 million viewers, the second-largest TV audience for any presidential or vice presidential debate since Nielsen started counting the number of persons watching debates in 1976.
Baltimore's TV market had the highest percentage of viewers, with 59.1 percent of TV households tuned to the event - about 660,000 homes. St. Louis, the city in which the debate was held, had the second-highest percentage of viewers at 58.3.
The largest national audience ever for a presidential debate was 80.6 million viewers on Oct. 28, 1980, for a meeting between Jimmy Carter and Ronald Reagan.
Among the vice presidential debates that previously ranked highest were the 1984 meeting between Geraldine Ferraro and George H.W. Bush, which drew 56.7 million viewers, and the 2004 encounter between John Edwards and Dick Cheney that was seen by 43.6 million.
Thursday's debate was carried on 13 networks: ABC, CBS, NBC, Fox, Telefutura, Telemundo, BBC-America, CNBC, CNN, Fox News Channel, MSNBC, PBS and C-SPAN. ABC had the largest audience with 13.3 million viewers. The audiences for PBS and C-SPAN were not included in the aggregate figure of 69.989 million because of differences in measurement procedures for noncommercial broadcasters.
While 1976 was the first year that Nielsen started counting persons watching rather than TV households due to advances in technology, the rating service measured household viewing for presidential debates back to 1960, when John F. Kennedy and Richard M. Nixon debated.
The ratings (which measure the percentage of TV households) for those debates were considerably higher than the ratings for Thursday's debate. Whereas Thursday's debate earned a 45.0 rating nationally, the largest Kennedy-Nixon showdown earned a 61.0 rating, though it was a radically different TV landscape in those days.