Truman holding Chicago Tribune that says "Dewey Defeats Truman"---Truman was so widely expected to lose the 1948 election that the Chicago Tribune had printed papers with this erroneous headline when few returns were in.
The United States presidential election of 1948 was the greatest election upset in American history. Virtually every prediction (with or without public opinion polls) indicated that incumbent President Harry S. Truman would be defeated by Republican Thomas E. Dewey. Both parties had severe ideological splits, with 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.
Is the Grand Old Party in as much disarray as it seems? Yup. For one thing, Republicans are electorally shellshocked. For the past couple of years, they had been confident Barack Obama would lose in November. Many Republicans held that belief going into Election Day. This was the first time since 1948 that Republicans were confident they were going to win a presidential election—and then lost it. The Republican psyche will take a while to recover from the shock of November 6.
November 1952 - General Dwight D. Eisenhower, a newcomer to politics, but popular due to his role in winning World War II as European commander, gains an easy victory over Democratic challenger Adlai E. The Electoral College vote was 442 to