"More Americans came into contact with maps during World War II than in any previous moment in American history. From the elaborate and innovative inserts in the National Geographic to the schematic and tactical pictures in newspapers, maps were everywhere. On September 1, 1939, the Nazis invaded Poland, and by the end of the day a map of Europe could not be bought anywhere in the United States. In fact, Rand McNally reported selling more maps and atlases of the European theaters in the first two weeks of September than in all the years since the armistice of 1918. Two years later, the attack on Pearl Harbor again sparked a demand for maps."