Pretty sure that the ruling liberals got Gunsmoke pulled off the air, like they did with Amos and Andy.
https://en.wikipedia.org/wiki/Gunsmoke
In September 1975, despite still ranking among the top 30 programs in the ratings, Gunsmoke was canceled after a 20-year run; it was replaced by Mary Tyler Moore spin-offs Rhoda and Phyllis (though Rhoda actually debuted while Gunsmoke was still airing first-run).
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There was a purge of the old guard programs at CBS. Hicks and hayseeds were off the air. No more Beverly Hillbillies or the rest. A new realism of urban dwelling liberals became the norm. They almost killed Gunsmoke in 1967.