Abraham Lincoln is one of the best-known U.S. Presidents; few realize, however, that he is the only President to have been issued a U.S. Patent. While traveling home between sessions of Congress in 1848, he observed boatmen float a flatboat off a sandbar. Lincoln, based on his observations, invented deployable pontoons to buoy vessels over hazards. On May 22, 1849, Lincoln was granted U.S. Patent No. 6,469 for his invention.