Truman isn’t just gleeful in that famous photo because he won the election, but because it was egg on the face of a paper he hated, the Chicago Tribune. The paper had a conservative bent, disapproved of most of his policies, and had once even called him a “nincompoop” in an editorial.
The Tribune was suffering under the weight of a strike, which meant its morning edition needed to go to press much earlier than in other election years - even before the polls closed.
Then as now, no serious news outlet wanted to report something after their competitors had gotten to it first, so the managing editor J. Loy "Pat" Maloney had to make a choice. He could take a chance and run with the outcome the polls were all predicting, or run with something less solid and risk no one buying the paper.
It didn’t really seem like a hard decision at the time. Every poll was saying New York Governor Thomas Dewey was going to reign victorious. Even the Tribune’s longtime Washington correspondent signed off on a Dewey win, and his article under the headline went so far as to say that Dewey won by an “overwhelming majority.”
Stop the Presses
Maloney approved the headline, and 150,000 copies of the early edition paper went to print. Before the papers hit the newsstands, though, he knew he might have made a mistake. New information was coming in that the race was closer than expected. For the second edition he changed the headline, ignoring the presidential race entirely and just running the results of the state elections.
Newspapers had written incorrect headlines before and people moved on; even in this instance, the Journal of Commerce had eight quickly forgotten articles about “President Dewey” in its special edition published on the same day as the Tribune’s headline. But two days later as Truman traveled back to Washington, he was handed a copy of the paper in front of reporters, presumably by someone who knew his feelings for the Tribune’s editorial staff, and the good-faith blooper went down in history.