What is a World Fair?
A world Fair was an international exhibition intended to show off the achievements of each nation, each one varies in location and theme. World Fairs started in London, running under the title "Great Exhibition of the works of industry of all nations", since then they have grown to form a better tomorrow.
What's happened to the world Fairs?
They haven't gone away but they are no longer held in the United States. Even though the Fairs still go on the themes have changed from space and imagination during the 60s to shifted focus on environment. Another issue with world Fairs is that they don't earn the host country any money, unlike the Olympics. They are still around but in other places, and maybe as soon as 2023 there may be a fair in America.