Reference maps show the boundaries and names of geographic areas for which the Census Bureau tabulates statistical data, but do not visualize the data.
In some cases, the name is only in the form of a geographic code, such as a census block number. Some types of reference maps show and identify geographic features that are part of the boundary. Examples are roads and water features.
Reference maps can include additional features such as railroads to aid users in orienting themselves to a place on the map.