Detailed map, colored by states and showing the newly acquired Alaska Territory and British Columbia (still British!). 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.