By the late 1960s, … many viewers, especially young ones, were rejecting [rural-themed] shows as irrelevant to modern times. Mayberry's total isolation from contemporary problems was part of its appeal, but more than a decade of media coverage of the civil rights movement had brought about a change in the popular image of the small Southern town. "Gomer Pyle, U.S.M.C.", was set on a U.S. Marine base between 1964 and 1969, but neither Gomer nor any of his fellow Marines ever mentioned the war in Vietnam. CBS executives, afraid of losing the lucrative youth demographic, purged their schedule of hit shows that were drawing huge but older-skewing audiences.