Set maps, or map series, constitute two or more maps of a specific location. Although differences abound, set maps usually are produced at a uniform scale, within a uniform time frame, in a uniform style, and by the same creator or its successor institutions. Depending on their scale of coverage, they can comprise anywhere from two to several hundred thousand maps. Coverage in many large to medium scale sets of maps is indicated by a graphic paper index and/or sometimes a list of sheets. Many sets do not have graphic indexes or lists, and may require a sheet-by-sheet search to identify a specific location.

Sets maps can be searched via the LC online catalog, with the search limited by Type of Material to "Map". Set maps can be identified by an "s" in the call number indicating the scale (e.g. G4380 s25 .U5, a set of maps at 1:25,000 scale). Because many sets are not described by either graphic indexes or lists, patrons must request assistance from reference staff if attempting to identify and use these materials.