The Baby Boomer's Poet Laureate

Ted Geisel, better know as Dr. Seuss, was born in 1904 in Springfield, Massachusetts, not far from a bustling street named Mulberry. Ted attended Dartmouth College and later acknowledged that he learned more from working at the student newspaper than in his classes. One night he was caught drinking on campus, and because this was the time of Prohibition the punishment was severe. He was expelled from college and lost his position as editor. Since he desperately wanted to continue his involvement with newspaper he came up with the pseudonym “Seuss” (also his mother’s maiden name) which later evolved into “Dr. Seuss”.
After a brief stint at Oxford University, where he met his wife Helen Palmer, he became a graphic designer and eventually developed a very successful career in advertising. Many of his characters like the Grinch, Horton and even the Cat in the Hat can be seen in his ads. During the WWII he worked at Warner Brother in Hollywood and created educational films for enlisted men. He learned a lot of about educating, while also entertaining. At Warner Brothers, Ted worked alongside Munro Leaf, The Story of Ferdinand.
Ted wrote his first children’s book while on a ship crossing the Atlantic. During a ferocious storm he needed a distraction and wrote the first draft of And to Think That I Saw it on Mulberry Street. The story was rejected 17 times before finding a publisher. Several years later, his editor at Random House made a bet that Ted couldn’t write a book using only 250 key words, and as a result The Cat in the Hat was created.
I’ll send a free copy of Theodor Seuss Geisel by Donald E. Pease to the first person who can successfully answer this question: What is the title of the last book that Dr. Seuss wrote and illustrated?