Massive map of Minnesota, colored by townships and showing railroads, canals, post offices, stations, etc. One of the best large format commercial atlas maps of the era. From one of the leading American map publisher of the 1870s.
O. W. Gray was a publishing firm based in Philadelphia. Later, they published as O. W. Gray & Son. They published atlases in the late nineteenth century. Gray's National Atlas was one of the most successful commercial ventures of the 1870s and one of the last to employ hand coloring on maps.