Glen Campbell/Leon Russell

It isn't accurate to call Glen Campbell "pure country," but his smooth fusion of country mannerisms and pop melodies and production techniques made him one of the most popular country musicians of the late '60s and '70s. Campbell was one of the leading figures of country-pop during that era, racking up a steady stream of Top Ten singles, highlighted by classics like "By the Time I Get to Phoenix," "I Wanna Live," "Wichita Lineman," "Galveston," "Rhinestone Cowboy," and "Southern Nights." Boasting Campbell's smooth vocals and layered arrangements, where steel guitars bounced of...