Released in tandem with “The Country Blues,” which remains in print, was an album of the same name containing 14 songs, little known and almost impossible to find at the time, recorded in the 1920s and ’30s by artists like Robert Johnson, Sleepy John Estes, Blind Willie McTell and Bukka White.

Mr. Dylan’s first album, recorded in 1961, included a version of Mr. White’s “Fixin’ to Die,” and within a decade other songs by the singers and guitarists whom Mr. Charters had highlighted were staples in the repertoires of blues and rock bands like the Allman Brothers, Canned Heat, Cream and the Rolling Stones.

Equally important, the aura of mystery Mr. Charters created around his subjects — where had they disappeared to? were they even alive? — encouraged readers to go out into the field themselves. John Fahey, Alan Wilson, Henry Vestine, Dick Waterman and other disciples tracked down vanished performers like Mr. White, Mr. Estes, Skip James and Son House, and their careers were revived. Their song catalogs were soon injected into folk and pop music.

“I always had the feeling that there were so few of us, and the work so vast,” Mr. Charters told Matthew Ismail, the author of the 2011 book “Blues Discovery.” “That’s why I wrote the books as I did, to romanticize the glamour of looking for old blues singers. I was saying: ‘Help! This job is really big, and I really need lots of help!’ I really exaggerated this, but it worked. My God, I came back from a year in Europe and I found kids doing research in the South.”

Mr. Charters had himself succumbed to the lure of field work. In 1958 he went to the Bahamas to record the guitarist Joseph Spence (who would influence the Grateful Dead, Taj Mahal and others), and a year later he helped revive the career of the Texas guitarist Lightnin’ Hopkins. He pursued overlooked music and artists on four continents for the next 50 years.