Theodor Seuss Geisel ( sooss GHY-zəl, zoyss -; March 2, 1904 – September 24, 1991) was an American children's author and cartoonist. He is known for his work writing and illustrating more than 60 books under the pen name Dr. Seuss ( sooss, zooss). His work includes many of the most popular children's books of all time, selling over 600 million copies and being translated into more than 20 languages by the time of his death.Geisel adopted the name "Dr. Seuss" as an undergraduate at Dartmouth College and as a graduate student at Lincoln College, Oxford. He left Oxford in 1927 to begin his career as an illustrator and cartoonist for Vanity Fair, Life, and various other publications. He also worked as an illustrator for advertising campaigns, including for FLIT and Standard Oil, and as a political cartoonist for the New York newspaper PM. He published his first children's book And to Think That I Saw It on Mulberry Street in 1937. During World War II, he took a brief hiatus from children's literature to illustrate political cartoons, and he worked in the animation and film department of the United States Army.