The major theme of the fair was to show that the United States was leading the realms of science and space. The US Government was really interested in demonstrating the nation's scientific prowess to the world, and so committed over $9 million to the fair, chiefly to build the NASA-themed United States Science Exhibit .
Another theme is to bring order to exposition scheduling and to make clear the rights and responsibilities of the host city and participants.Approximately 10 million people attended this fair and The Century Twenty One made a profit as well.
The farmers in Sumer created levees to hold back the floods from their fields and cut canals to channel river water to the fields. The use of levees and canals is called irrigation, another Sumerian invention
