Among the covers designed by W. W. Denslow for Rand McNally is this atlas, The World's Peoples and the Countries They Live In. This is a combination atlas and geography book, with many maps, photos and diagrams of various countries and their inhabitants. The cover is designed in quite a different style from the books I've been showing - it's a much more detailed drawing, rather than a bold graphic image. The size of the atlas allows for this approach, since there is plenty of room for detail and less necessity for simple blocks of color.
I'm afraid this image was somewhat inexpertly pieced together from two scans, as the book is too large for my scanner - but at least you get the idea!