So how popular was Barack Obama‘s final speech to the Democratic Party’s last session last Thursday evening in Denver?

Very, with an enormous number of whites watching and almost a quarter of all American households tuning in, over two and a half times the number of households who watched the final day of the 2004 convention.

It beat American Idol‘s finale on Fox in May and it also beat the Beijing games opening on NBC last month. It also beat president Bush’s State of The Union speech in January, his last. More people watched Obama’s speech than watched the Oscars in February.

Just under 25% (24.5%) of all American homes watched the part’s final day, featuring Obama’s acceptance speech. It was carried on 10 TV networks, on free to air or cable, live for the speech. It wasn’t measured on public broadcasting.

Nielsen said the convention was carried live during prime time on ten networks on Thursday night for Obama’s speech: ABC, CBS, NBC, CNN, FOX News Channel, MSNBC, BET, TV One, Univision and Telemundo. All ten aired live coverage from approximately 10-11PM (East Coast Time).

According to the Nielsen company, which does TV ratings in the US, more than 38.3 million people watched the speech, compared to 35.3 million who watched the opening ceremony of the recent games and around 31.7 million who watched the finale of Idol in May, 32 million watched the Oscars.

More than 17.4 million people watched the speech on the three main free to air networks with ABC number one on the night with 6.58 million, NBC was second with its coverage being watched by 6.10 million and CBS’s coverage averaged 4.72 million.

All things being equal, it could end up as the second most popular broadcast on TV this year in the US after the Super Bowl (or third if election night is close in November).

More people watched Obama’s acceptance speech than speeches to the convention from Hilary Clinton (26 million) and Bill Clinton (24 million), according to Nielsen’s figures.

Nielsen said 26.05 million viewers on the Thursday were white, 7.54 million were African American and 5.2 million were Hispanic. More whites (more than 21 million) watched the four days of the convention on the four day average total audience in 2004 of just over 20 million.

Nielsen said the speech was the 5th most watched TV program for African Americans in the history of TV ratings: the top four were all TV tele movies.

Compared to the 2004 convention’s fourth day (the high point with the acceptance speech by Senator John Kerry), nearly 14 million more people watched Obama, or almost 58% more than the 24.4 million who watched four years ago. The rating then was 8.9% compared to the 24.5% for the 2008 final day.

The average for each of the four days watching (live and replay) was 30.2 million versus 20.4 million in 2004 for the live only part of that convention.

The TV coverage, live and pre-recorded for this convention was significantly expanded on 2004.