Nielsen says that the first presidential debate was watched by 52.4 million viewers — more than ten million less than watched the first Bush-Kerry debate four years ago.

Given that just about every debate and political-oriented broadcast has posted high ratings this cycle, it’s a bit of a surprise. But not when you consider that the debate aired on Friday night, traditionally the second lowest night of the week for watching TV.

The most-watched presidential debate was Jimmy Carter and Ronald Reagan’s October 28, 1980 debate with 80.6 million viewers, although Nielsen didn’t keep records in 1960, the first televised forum with Richard Nixon and John F. Kennedy.

By contrast, the Friday debate does not even make it into the top ten.

African American viewership ran ahead of the population as a whole, with Hispanics watching at a lower rate than the rest of the audience.