Yeah, I know they still have them but the ones that I've seen in the last few decades seemed pretty tame, as compared to what I remember from the early days. Growing up, there were a couple of race tracks in northern Wisconsin that we'd go to sometimes and, while I wasn't particularly excited about the races, they always had a demolition derby after the race, and those were always exciting. Maybe I was just more excitable then.
When I was a kid my grandmother or my father would always take us to the demolition derby on the last day of the state fair. I'm not 100% sure but I think that they finally did away with them in 2015 along with an annual stock car race.