All across the country this month, schools have been celebrating the birthday of Theodor Geisel, aks Dr. Seuss, who was born on March 2, 1904. Although he died in 1991, Dr. Seuss’ vivid illustrations and whimsical rhymes have made him a mainstay of children’s literature. His influence has been seen increasingly in films as well. Horton Hears a Who, based on the Seuss book of the same name, is in theaters now.

Dr. Seuss’ first book was And To Think That I Saw It On Mulberry Street, but it was The Cat in the Hat that came to define his career. The book was the result of an endeavor to create a chilren’s book using only 225 beginning reader words. To this day, the tall, red-and-white-striped hat worn by the title charater is synonomous with the author.

Dr. Seuss wrote and illustrated 44 chilren’s books including Green Eggs and Ham, How the Grinch Stole Christmas and perennial graduation favorite Oh, the Places You’ll Go.