Moving mail from one location to another is the primary function of any postal system. The complex transportation network that links those locations relies on maps to aid route selection and to ensure and speed communication. Since the late eighteenth century, the post office has commissioned cartographers to draw maps for this purpose. These maps have been critical to mail transportation locally, nationally, and globally.
Maps continue to help postal officials determine the best routes between locations based on topography and population centers. They inform the reorganization of carrier routes to reach growing cities or burgeoning suburbs. They help officials plan the allocation of potential resources by tracking population growths and shifts.