The famous CBS “Rural Purge” of the late-60s/early-70s. CBS was derisively call The Country Broadcasting System by the other networks. CBS shows were extremely popular but sponsors said that the viewing demographics of CBS’ programming weren’t buying enough of their products. Network executives wanted to win audiences that spent money and that skewed hip, young, urban...or so it was said at the time.
The Wild Wild West, Green Acres, Petticoat Junction, The Beverly Hillbilies, The Andy Griffith Show, Gomer Pyle, (Hee-Haw, too, I think,) and a slew of other Country and Western-themed shows were canceled to make way for All In The Family, MASH, and other more contemporarily-themed and topical shows. Gunsmoke was, I think, the only Western to surive The Purge. One of the stars of Green Acres once declared that (IIRC), “1968 was the year CBS began killing every show with a tree in it!”