Wikipedia has an excellent article on the complicated and fascinating history of Gunsmoke:

http://en.wikipedia.org/wiki/Gunsmoke

Milburn Stone (1904-1980), who played Doc Adams for the show’s entire run, was himself a native of Kansas and the old timers he knew as a boy were among the first white settlers of the Sunflower State. He played the real thing.

Dennis Hopper was a native of Dodge City and he guest starred in the 1965 episode “One Killer on Ice”.

One gauge of the show’s enduring popularity is that it is currently airing on two cable channels here in the States. TVLand has shown the hour-long color episodes from 1966-75 since its founding in 1996. The Encore Westerns Channel aired the hour-long black & white episodes of 1961-66 in 2002-05 and again since January 2010.