In 1948, the Chicago Tribune jumped the gun and mistakenly declared New York Governor Thomas Dewey the winner of his presidential race with incumbent Harry S. Truman in a front-page headline: “Dewey Defeats Truman". In a now famous photograph snapped in the early morning hours after the election, a beaming and bemused Truman is shown holding aloft the Chicago Daily Tribune issue that had wrongly predicted his political downfall. President Truman in fact defeated Dewey by 114 electoral votes.

Overall, considering all the facts, the election is considered to be the greatest election upset in American history. Virtually every prediction (with or without public opinion polls) indicated that Truman would be defeated by Dewey. The Democratic Party had a severe three-way ideological split, with both the far left and far right of the Democratic Party running third party campaigns. Truman's surprise victory was the fifth consecutive presidential win for the Democratic Party, the longest winning streak in the history of the party. It was believed that Truman's election confirmed the Democratic Party's status as the nation's majority party.

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