Beginning in 1943, the earliest paperback books published by Dell Books are referred to 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 with Mapbacks extending from #5 to at least #550; then maps became less of a fixed feature and disappeared entirely in 1951.

The artwork of the maps began with quite detailed maps, and later contained more stylized ones. Dell's most memorable design innovation was not on the front but on the back covers ... the entire back covers given over to maps, or variously charts, blueprints, or what have you to represent story locale or scene of the crime: a stretch of California highway, the interior of an apartment, a sheik's 'city of stones.' It was an enjoyable if slightly goofy gimmick and, amazingly, managed to last nearly ten years.