The Key West City Commission exempted the home from a city law prohibiting more than four domestic animals per household. About 50 cats live there.
The house has been locked in a dispute with the USDA, which claims the museum is an "exhibitor" of cats and needs a special license, a clwriteaim the home disputes.
The new ordinance, approved Tuesday, reads in part, "The cats reside on the property just as the cats did in the time of Hemingway himself. They are not on exhibition in the manner of circus animals. ... The City Commission finds that family of polydactyl Hemingway cats are indeed animals of historic, social and tourism significance."
It also states that the cats are "an integral part of the history and ambiance of the Hemingway House."
A USDA spokesman did not return messages left late Sunday.
The cats are descendants of a six-toed cat given as a gift to the writer in 1935. All carry the gene for six toes, though not all display the trait.