Is a map a primary source?

A map can be a primary or secondary source. If a map was produced as immediate evidence of an area, then it is a primary source. If the map is just a symbolic depiction of a space then it is a secondary source. For example, maps of Hispaniola made by Columbus in the 1490s are primary sources, but a map created in 2005 showing Columbus' first conquered land is a secondary source.

A map that you made on a scrap of paper of the layout of a piece of land you saw can be used as a primary source. In this sense, Columbus maps of Hispaniola and your sketch are direct evidence of an area, hence primary sources. In contrast, a sketch you made of an area you have not seen and the map of Columbus' first conquered land made in 2005 are not direct accounts of a surface, making them secondary sources.

To illustrate further, the map below can be used as a primary source in a study about the development of telegraph lines between 1791 and 1872. Nevertheless, it would be classified as a secondary source in an analysis about maps of the world.

Map of telegraph lines 1855
Example of a map that is used as a primary resource: Map of Telegraph Lines (1855). Image source: http://hdl.loc.gov/loc.mss/mmorse.071004