Theodor Seuss Geisel was born on March 2, 1904, in Springfield, Mass. No one could have guessed then that Theodor would become a world-renowned children’s author known simply as Dr. Seuss. Many of his works are impossible to avoid, including Green Eggs and Ham, The Cat in the Hat, as well as How the Grinch Stole Christmas! But what was the first book Dr. Seuss wrote?

Here’s a look at some of the numbers behind his illustrious career, as well as an answer to our title question.

The Name ‘Seuss’ First Appears in Print

The man who would become Dr. Seuss attended Dartmouth College in Hanover, N.H. There, he served as editor in chief of the school’s humor magazine — Jack-O-Lantern. But Dr. Seuss chose to have a few drinks with friends in his dorm room, which was a big no-no during Prohibition. And he was kicked out the magazine’s staff.

So he started writing under a pseudonym — Seuss.

After Dartmouth, he attended Oxford. He met his future wife, Helen, and they were married in 1927. He was planning to become a college professor. But then he had a change of heart. He wanted to become a cartoonist, and so he moved back to the United States.

Working for Major Publications

His work soon appeared in major publications like LIFE, Vanity Fair and The Saturday Evening Post. It was in a Post article that he again wrote using the name “Seuss.” He worked for Standard Oil’s advertising department, too, and one of his ads earned national recognition.

He also illustrated a children’s book called Boners, which didn’t meet with much financial success — but it certainly got him into the children’s literature arena. When returning from an ocean voyage to Europe in 1936, Dr. Seuss listened to the churning of the ship’s engine and created a poem to match its rhythm.

That poem became what was the first book Dr. Seuss wrote: And to Think I Saw it on Mulberry Street.

Facing Down Rejection

The story of And to Think I Saw it on Mulberry Street focused on all that a young man named Marco observes as he walks from his home to school one day. Once the writing and the illustrations were complete, Dr. Seuss began submitting them to publishers.

He was rejected again and again — 27 times in all.

He had decided to give up and burn the manuscript. But then he ran into Mike McClintock, and old college buddy, who had just started as an editor at the publishing house Vanguard Press. Mike introduced Dr. Seuss to two Vanguard executives, and they agreed in 1937 to print 15,000 copies of And to Think I Saw it on Mulberry Street.

The Rest is History

Of course, the book sold well enough that it required a second run. Vanguard continued publishing And to Think I Saw it on Mulberry Street until 1988, when the publishing house was purchased by Random.

Dr. Seuss spent time during World War II animating training films and creating propaganda posters as part of Frank Capra’s Signal Corps. But, after the war ended, he moved to La Jolla, Calif., where he resumed writing and illustrating books for children.

Dr. Seuss Meets Tragedy

Sadly, Dr. Seuss’s wife Helen committed suicide in 1967. She had struggled with cancer as well as the emotional pain of an affair Dr. Seuss carried on. A year later, Dr. Seuss married Audrey Stone Dimond, the same women with whom he’d had an affair. Dr. Seuss never had any children of his own.

The End of a Stunningly Successful Career

Dr. Seuss continued working until his last days. He died in 1991 at the age of 87 in La Jolla. In addition to the many works published during his lifetime, manuscripts and sketches were found in his office that are being used to continue churning out new works by the famed Dr. Seuss.

See below for a look at some of the numbers behind Dr. Seuss’s career, and check out the best Dr. Seuss books that you or your children can try out.

What Dr. Seuss book means the most to you? Let us know in the comments section below, or reach out to us directly through our contact page.