The first recorded instance a President of the United States taking to the skies happened on January 14th, 1943 - and we have a picture of the occasion! Here's Franklin D. Roosevelt looking happy to be on board The Dixie Clipper - a Boeing 314.
Roosevelt was on his way to meet British Prime Minister Winston Churchill to discuss war strategy in Casablanca. On the way to Morocco, the plane touched down in Brazil and Gambia to pick up fuel and supplies.