Many Americans became familiar with the term "no-fly zone" following the 9/11 attacks, when one was established around Washington, D.C., but the concept is not much older than that. The first no-fly zone was actually imposed in Iraq in 1991 as part of the cease-fire agreement that ended the Gulf War. A no-fly zone doesn't always mean that no planes can fly over that area. It's hard to pin down how many no-fly zones there are in the U.S. because, as the FAA terminology implies, they are often not permanent. Kennedy Space Center in Florida is one — at least during rocket launches — but did you know that when you visit Cinderella's Castle at Walt Disney World in Orlando, you're protected by a no-fly zone?