Today's date in history, from Writer's Almanac:

It was on this day in 1948 that Harry S. Truman (books by this author) accomplished one of the greatest upsets in an American election by beating the governor of New York, Thomas E. Dewey, for the presidency ... Truman was not all that popular. Republicans had retaken control of the Congress in the midterm elections in 1946, and there was a sense in the country that the New Deal was dead ... Two months before the election, the pollster Elmo Roper announced that he was going to stop surveying voters, because Dewey was so far ahead. He said, "[I've decided to] devote my time and efforts to other things." The most recent poll had shown Dewey leading Truman by 44 to 31 percent.
But Truman set out on one of the most ambitious campaigns in American history. He had a private railroad car outfitted for a cross-country journey that became known as the "whistle-stop tour." He would pull into a train station in a small town and give a speech directly from the train, which was equipped with a sound system. That fall of 1948, he covered 21,928 miles, and he managed to deliver more than 300 speeches around the country ... All the major newspapers in the country still predicted his defeat, but Truman privately estimated that he would win about 340 electoral votes, and Dewey would get about 108 ... It turned out that Truman had won 303 electoral votes to Dewey's 189. Of the popular vote, he won 24 million to Dewey's 22 million. Not one news organization in the country had predicted the election correctly.
It was two days after the election that Truman was making an appearance in St. Louis and somebody handed him a copy of the Chicago Daily Tribune that had run the day before with the headline, "DEWEY DEFEATS TRUMAN." Truman held the paper up over his head for the photographers in attendance, and that picture became the most famous picture of Truman ever taken.

I am a fan of Truman for many reasons, and this is one of them. (I've shortened the original post)