I live in Knoxville, and was 9 when the World's Fair was going on. I remember just a little bit...I only went once or twice b/c it was so expensive. There were pavillions for different countries...I remember the German pavillion with the beer-cooked hotdogs, and shows at the Japanese pavillion.
I think the pp who mentioned cost hit the nail on the head. Other than the Sunsphere, and World's Fair park...nothing remains from the World's Fair. The pavillions got run down, and it cost the city lots of money to either fix them up or tear them down. They tore them down (the last to go was the US pavillion) b/c no one wanted to rent or use it after the fair.
It brought a lot of money to our area in 1982, but then after that became a big money sink. Thankfully, the land is now used for concerts, and there is a nice fountain park for the kids. The country flags and the Sunsphere are the only fair reminders. And the Sunsphere stood empty and unused for a long time...it is just now being renovated, and I hope to take my kids up to see if from the inside.
Anyways...I'm rambling. But just my take on the fair.