The "Hardy Boys" volumes were extensively revised beginning in 1959 at the insistence of publishers Grosset & Dunlap, and against the wishes of Harriet Adams. The revision project, which also encompassed the "Nancy Drew Mystery Stories", was sparked largely by letters that parents had been writing to Grosset & Dunlap since at least 1948, complaining about the prevalence of racial stereotypes in the books. Volume 14 in the "Hardy Boys" series, "The Hidden Harbor Mystery" (1935), was singled out for particular and repeated attention for its portrayal of a black criminal who organizes a gang of black boys and treats whites disrespectfully. As one parent put it, the books were "ingraining the old race-riot type of fear." As such letters became more frequent, Grosset & Dunlap informed the Stratemeyer Syndicate that the books must be revised and such stereotypes excised. The end result, however, was less the removal of stereotypes than the removal of non-white characters altogether and the creation of an "ethnically cleansed Bayport." By the 1970s, however, the series began to re-introduce black characters.