The 1939–40 New York World’s Fair, which covered the 1,216 acres of Fountain Lake, was the second largest American world’s fair of all time. Many countries around the world participated in it, and over 44 million people attended its exhibits in two seasons. The NYWF of 1939–1940 was the first exposition to be based on the future, with an opening slogan of “Dawn of a New Day”, and it allowed all visitors to take a look at “the world of tomorrow”. According to the official New York World’s Fair pamphlet:
"The eyes of the Fair are on the future — not in the sense of peering toward the unknown nor attempting to foretell the events of tomorrow and the shape of things to come, but in the sense of presenting a new and clearer view of today in preparation for tomorrow; a view of the forces and ideas that prevail as well as the machines. To its visitors the Fair will say: "Here are the materials, ideas, and forces at work in our world. These are the tools with which the World of Tomorrow must be made. They are all interesting and much effort has been expended to lay them before you in an interesting way. Familiarity with today is the best preparation for the future.’"
More details: http://en.wikipedia.org/wiki/1939_New_York_World’s_Fair