According to data from across 11 networks, the first presidential debate on September 26 between John McCain and Barack Obama drew 52.4 million viewers.
The TV audience for the first presidential debate of the 2008 election was roughly 16% smaller than the audience for the first debate between President Bush and John Kerry during the 2004 election, which drew 62.5 million viewers on September 30, 2004. See more historical debate ratings.
ABC, CBS, FOX, NBC, Telefutura, Telemundo, BBC-America, CNBC, CNN, FOX  News Channel, and MSNBC aired live coverage of the McCain/Obama debate …

The combined overall household rating for Friday night’s presidential debate, in 55 of the 56 local television markets where Nielsen maintains electronic TV meters, was 34.7.
One rating point equals 1% of the total TV audience in a given market.
Coverage of the first presidential debate between Barack Obama and John McCain aired on ABC, CBS, NBC, FOX, PBS, CNN, Telemundo, TeleFutura, BBCA, Fox News, MSNBC, and C-Span.
Previously, Nielsen reported that the combined overall household rating for the top 55 local markets was 33.2. That rating excluded households that …