NOAA considers a historical map or chart any map or chart that is not used today because it is out of date
The Office of Coast Survey maintains a historical map and chart collection of over 35,000 scanned, high-resolution images. The collection includes some of the nation’s earliest nautical charts, bathymetric maps, city plans, and Civil War battlefield maps.
Nautical charts are one of the most fundamental tools available to mariners, depicting the nature and form of the coast, the general configuration of the sea bottom, water depths, locations of dangers to navigation, locations and characteristics of human-made aids to navigation, and other features useful to the mariner.
Additionally, many of historical charts also depict events reflecting the geographic landscape at that time. For example, within the Office of Coast Survey's collection is a Chattanooga battlefield map from 1863 which is considered one of the best Civil War maps at that time.
While the historical map and chart collection dates back to the 1700s, the Office of Coast Survey, which formed in 1807 as the first federal scientific agency, produced its first charts in the early 1840s.
Electronic copies of images within the collection are available, by free download, to the public.
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Original article: What is a historical map or chart?