The Chicago Daily Tribune published the erroneous headline "Dewey Defeats Truman" (pictured) in its early morning edition shortly after incumbent U.S. president Harry S. Truman officially upset the heavily favored governor of New York Thomas Dewey in the presidential election.

The Chicago Tribune is an American daily newspaper based in Chicago, Illinois, United States. Founded in 1847, it was formerly self-styled as the "World's Greatest Newspaper", a slogan from which its once integrated WGN radio and WGN television received their call letters. It is the most-read daily newspaper in the Chicago metropolitan area and the Great Lakes region, and the sixth-largest newspaper by print circulation in the United States.

"Dewey Defeats Truman" was an erroneous banner headline on the front page of the earliest editions of the Chicago Daily Tribune on November 3, 1948, the day after incumbent United States president Harry S. Truman won an upset victory over his opponent, Governor Thomas E. Dewey of New York, in the 1948 presidential election. It was famously held up by Truman that day at a stop at St. Louis Union Station following his successful election, smiling triumphantly at the error.

Harry S. Truman was the 33rd president of the United States, serving from 1945 to 1953. As the 34th vice president in 1945, he assumed the presidency upon the death of Franklin D. Roosevelt that year. Subsequently, Truman implemented the Marshall Plan in the aftermath of World War II to rebuild the economy of Western Europe, and established both the Truman Doctrine and NATO to contain the expansion of Soviet communism. A member of the Democratic Party, he proposed numerous New Deal coalition liberal domestic reforms, but few were enacted by the conservative coalition that dominated the United States Congress.

Thomas Edmund Dewey was an American lawyer and politician who served as the 47th Governor of New York from 1943 to 1954. He was the Republican Party's nominee for president of the United States in 1944 and 1948, losing the former election to Franklin D. Roosevelt, and the latter election to Harry S. Truman in a major upset.