NEW YORK (AP) -- In a close election campaign with both sides looking for an edge, the party with more people watching their midsummer convention would seem to have an important sign of success.
Yet historically speaking, that measurement means next to nothing.
Eight times over the past 16 presidential election cycles dating back to 1960, the party with the most popular convention among television viewers won in November. Eight times they lost.
Through the first three nights of each convention this summer, the Democrats averaged 20.6 million viewers, the Nielsen company said. Republicans averaged 17 million in July. The estimate for Thursday night, highlighted by Vice President Kamala Harris' acceptance speech, is due later Friday.
"It's one of those interesting things about covering politics is that you see these indicators about what really matters, and a lot of times it doesn't," said veteran journalist Jeff Greenfield, who covered the Democrats this week for Politico.
The Democratic convention has been more popular with viewers in 12 of the last 16 elections, Nielsen said. Although Democrats have won eight of those elections, their candidate recorded the most votes in 10 of them.
The last time a party lost despite having a more popular convention was in 2016, although it was close: Democrat Hillary Clinton's nominating session beat Donald Trump by less than a million viewers per average, Nielsen said. For all of his vaunted popularity as a television attraction, Trump fell short in the ratings twice and is on track to make it three.
A convention's last night, with the nominee's acceptance speech, generally gets the most viewers. Trump reached 25.4 million people with his July speech, less than a week after an assassination attempt, and the average would have undoubtedly been higher if his 92-minute address hadn't stretched past midnight on the East Coast.
Despite Barack Obama's historic election as the nation's first Black president in 2008, Republican John McCain's convention actually had more than 4 million viewers each night on average.
For four straight cycles, between 1976 through 1988, the party with the most-watched convention lost the election. That included the two lopsided victories by Republican Ronald Reagan -- although a nomination fight between Jimmy Carter and Ted Kennedy in 1980 and the selection of Geraldine Ferraro in 1984 as the first woman on a national ticket probably boosted the Democrats' convention audience in those years.
Typically, people are more likely to watch their own party's convention, Greenfield said. That's reflected in the ratings this year: Fox News Channel, which appeals to Republicans, had by far more viewers than any other network for the GOP convention, while left-leaning MSNBC has dominated this past week.
It will also be interesting to see if star power -- or potential star power -- boosted Harris. Rumors of a surprise Beyoncé or Taylor Swift appearance, ultimately unfounded, hung over the Democratic session.
Both conventions are highly produced television events as much as they are political meetings, and Greenfield said it was clear the Democrats had the upper hand.
"I think if you were going strictly on entertainment value," he said, "Oprah Winfrey and Stevie Wonder trump Kid Rock and Hulk Hogan."
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David Bauder writes about media for the AP. Follow him at http://twitter.com/dbauder.
