It was three spectators killed at Charlotte in 1999 by that flying wheel.
As for the third oval in that template, Atlanta was dropped after 2001, in no small part, I'm sure, due to that 12-car pile-up that injured three or four drivers. This should have also been a wake-up call that would have hopefully precluded what occurred at Las Vegas in 2011.
https://www.youtube.com/watch?v=BW3MlDUq0CI