Mapback is a term used by paperback collectors to refer to the earliest paperback books published by Dell Books, beginning in 1943. The books are known as mapbacks because the back cover of the book contains a map that illustrates the location of the action. Dell books were numbered in series. Mapbacks extend from #5 to at least #550; then maps became less of a fixed feature of the books and disappeared entirely in 1951. (Numbers 1 through 4 had no map, although a later re-publication of #4, The American Gun Mystery by Ellery Queen, added a map.) The occasional number in the series between #5 and #550 contains no map, but some sort of full-page graphic or text connected with the book’s contents. … the Dell ‘mapbacks’ are among the most well known vintage paperbacks.
I wasn’t aware what the term “mapback” really meant until I came across the book I’m reading right now: Helen McCloy “Cue for Murder” Dell Mapback #212. And I thought it was worth sharing it for those who might not be familiar with this term.