but in the lower 48, the best belt is still yell localstone. >> back in the 1970s, old faithful had some real competition also the crowd favorite because back then, there were grandstands like this set up at the yell localstone dump. tourists would line up to watch the bears feast on their garbage. when rangers decided to cult off that free lunch, it was devastating. the animals forgot how to field themselves. thousands starved to debt and the grizzly became endangered. to get a sense of how they are faring today, casey will take us into the grizzly grounds just north of the park. after a quick lesson in self-defense. >> this is bear pepper spray. >> reporter: with a nose seven times more sensitive than a blood hound, a blast of nonlethal pepper spray sends them scampering. what about if i say, i don't know, ran, as fast as i could for the rental car? what would the bear do then? >> a grizzly bear runs as fast as a racehorse. which is getting close to 40-mile-an-hour range. >> reporter: bear mace on our hips, we head into the hills. kay similar's crimes flicking from the horizon to the t