The Arctic region. Historic map, Library of Congress

Shows southern boundary of continuous permafrost ground and Northwest Passage/Northern Sea Route.
"78635 7-70."
North Pole at map center.
Vertical meridian at 100°W/80°E.
Available also through the Library of Congress Web site as a raster image.
LC copy imperfect: Annotated in black marker ink/lead-pencil, taped at edges.
Includes note.