(1) A map showing the general location and coverage of other maps, aerial photographs or points of interest. (2) A map showing the location, sheet lines and reference codes of maps in a map series.

Reference map sheet which outlines a mapping area and identifies all map sheets or sub-map sheets required to see the entire mapping area in detail.

A map which is used as a reference in the location of the more detailed, large scale maps needed for a particular project. Typically index maps do not contain detail beyond that necessary to locate the map required, by name, location or other relevant identifying information.

Map, usually at a small scale, used to identify an individual map within a series

a generalized map showing outlines and boundaries of certain features

an outline of the entire area that shows the layout and numbering or naming of the maps sheets

(1) A map of smaller scale on which are depicted the locations (with accompanying designations) of specific data, such as larger-scale topographic quadrangles or geodetic control. (2) Photography: A map showing the location and numbers of flight strips and photographs.

A map showing the location of all the USGS quadrangles in a given state. Map Express can provide free state indexes through the mail, or you may use our new online map index here.

A map prepared to serve as a key by which a section map in a city, town or village may be readily located.

Diagram showing which sheet in a map series covers which area.

Maps that show the location or coverage of other maps. Examples are the soil survey map sheet index and the USGS topographic quadrangle index.

See Framework map.