this was terry sorensen's first time in the roundup. >roundup. >> reporter: when you're out there in the herd, what's it like? >> very exciting, racing along. wind flying and buffalo and everything like that. it was a lot of fun. >> reporter: after participating in 40 roundups, bob landis knows why the crowds have grown from a few hundred to a few thousand spectators. >> cracking the whips and yelling, you get into it. and they're rooting, i think basically for the buffalo. >> reporter: and it's no wonder that crowds today root for the buffalo, considering its tortured past in this country. the buffalo here are direct descendents of five wild calves, rescued by a rancher in 1963. they were this close to extinction. a combination of agreed and government policy nearly wiped out these magnificent creatures. in nearby rapid city, we found a museum dedicated to telling that terrible tale inside, founder, susan reeky showed us a photograph of buffalo skulls piled several stories high. >> reporter: what are we seeing? >> it's a stunning pictu