The boundary with New York is placed at about 42d 30m and called undefined. This is the first map of the state of Pennsylvania itself, rather than the Philadelphia or Mid-Atlantic regions. It pre-dates the larger and better known 1759 Scull map of Pennsylvania by three years. The Delaware separation from Pennsylvania is not shown. See the 1773 map.
Longitude is west from Paris.
There were two Mr. Armstrongs, brothers George and John. This map is usually attributed to Major George Armstrong due to a long ago note made on the back of it and some correspondence between John Armstrong and Governor William Denny. A number of manuscript maps of western Pennsylvania were produced during the 1750's because of the fighting against the French. Maps assumed to be by William Alexander, George and John Armstrong, and Thomas Hutchins from this era are discussed by Myers with reproductions, who questions the dating and maker of this map. This map is based upon a drawing by Capt.