For seven months in 1904, St. Louis was the greatest city on earth. Millions flocked to the Louisiana Purchase Exposition to behold the inventions of the early 20th century. Many saw electric lights, automobiles, aircraft, and moving pictures for the first time. At a time when few traveled more than a couple miles from home, visitors encountered the people and cultures of faraway lands. It was an educational experience, a "university of mankind." The Pike offered amusement rides, wild animal displays, and fanciful trips through the Hereafter and Creation exhibits. Fairgoers visited the Alps,...