This is a very nice United Airlines promotional brochure featuring ten distinctive pictorial maps. The maps detail the air trails across the United States as flown by United Airlines in the late 1930's.  Each map is densely filled with Ruth Taylor's playful images of the area.  The newly created Boulder (Hoover) Dam - 1935 - is shown suggesting a publication date in the late 1930's.  Passengers were given this brochure as a souvenir of their flight in the innovative DC-3 aircraft.