Dr. Seusss political leanings are well knownhe was a liberal Democrat who opposed fascism in the 1940s and President Nixon in the 1970s. The new movie of his book The Lorax is a fairly unsubtle pro-environment allegory.
Less well celebrated are Theodor Seuss Geisels early advertising and political cartoons from the 1920s through the 1940s, which feature a decidely racist streak. ...
In the ads (from the collection of the library of the University of California, San Diego), black people are presented as savages, living in the tropics, dressed in grass skirts. Arabs are portrayed as camel-riding nomads or sultans. In his political cartoons (from the collection of the Springfield Library and Museums Association), Seuss inveighed against the Japanese during World War II; he drew them buck-toothed and squint-eyed. ..."
http://www.businessinsider.com/before-dr-seuss-was-famous-he-drew-these-sad-racist-ads-2012-3
“Less well celebrated are Theodor Seuss Geisels early advertising and political cartoons from the 1920s through the 1940s,”
Operative word: EARLY.
Later works with orders-of-magnitude greater impact atone for earlier less-known cultural-norm content.