I'm visiting Durango, Colorado this week and after rolling into town I discovered there was a show of original Dr. Seuss drawings!! I feel like I won the lottery!
Here is a photo by Steve Lewis that I grabbed from this Durango Herald article. There's also a nice article from The Durango Telegraph.
Next to each drawing from one of his stories, they displayed a copy of the finished book open to the same page. It was fun to compare the rough sketch with the finished version in the published book. Many of them were done on tracing paper. With some drawings, he also used the tracing paper to do color separations. Lines were done in pencil and some of them were inked with black ink. Then he planned out the color by coloring in big areas loosely with colored pencil. In his early books he only got to use 2 or 3 colors besides black and white. He could also use a lighter or more dense version of a color for variation. Fo example, a wall was colored completely in blue pencil an there was a note saying "blue 100%." Then there might be a character with lighter blue hair on the same spread with a note saying "blue 70%." And in another spot on the page a pale blue book cover with a note saying "blue 30%."
There were also some finished paintings from his books and some political cartoons. And in a corner for the kids, a reading area with heaps of Dr. Suess books. Do you know he published 46 children's books?!
If you're interested, you can see his political cartoons here. And his advertising artwork here.