The artist used pen and ink and white gouache to create the scene. The photos show foxing and discoloration around the edges, but that will be significantly reduced with proper matting.
Google Silver Sage and Carson City and you will find Silver Sage Drive, running south from Carson City and now very developed with homes, shopping malls, etc. I have not been able to find anything specific about the Silver Sage Hotel, but by the drawing it was a crescent shape, with a huge 8-shaped swimming pool, tennis courts and probably a horse riding corral.