`` Dewey Defeats Truman '' was an incorrect banner headline on the front page of the `` Chicago Daily Tribune '' on November 3 , 1948 , the day after incumbent United States President Harry S. Truman won an upset victory over Republican challenger and Governor of New York Thomas E. Dewey in the 1948 presidential election .
It was published on November 3 , 1948 . It happened the day after incumbent United States President Harry S. Truman won an upset victory over Republican challenger and Governor of New York Thomas E. Dewey in the 1948 presidential election .