"The illustration referred to was originally done for the seventh novel of the series and can be found in that book. It was painted to illustrate the scene near the end of the story just after Susannah rides her motorized trike thru the door into another reality. The Gunslinger is left behind in grief. As described in the text, Roland sits in front of the door with his head in his hands, and that is what I painted. I don't know if it shows up on the cover of the concordance or not, but in the version featured in THE DARK TOWER one can easily read the sign on the door which says "The Artist"...because the door was created by Patrick the magic artist for Susannah.
The tread marks are from her motorized ATV."