 The Cat in the Hat 's popularity also led to increased popularity and exposure for Geisel 's previous children 's books . For example , 1940 's Horton Hatches the Egg had sold 5 @,@ 801 copies in its opening year and 1 @,@ 645 the following year . In 1958 , the year after the publication of The Cat in the Hat , 27 @,@ 643 copies of Horton were sold , and by 1960 the book had sold a total of over 200 @,@ 000 copies . 
