Not illegal in the states, unless it's something intended to encourage people to do something illegal right that moment and likely to work. We allow Klan rallies, but not saying "let's go lynch that guy."actively promoting hate speech (Illegal in CAN where I'm from, not sure about here).
In Canada, hate speech is anything "intended or likely to circulate extreme feelings of opprobrium and enmity against a racial or religious group". The landmark case being Her Majesty The Queen V. James Keegstra, who interestingly, was also a public school teacher:In 1984, he was charged under section 281.2(2) of the Criminal Code [now 319(2)] ("Every one who, by communicating statements, other than in private conversation, wilfully promotes hatred against any identifiable group")[1] for "promoting hatred against an identifiable group by communicating anti-semitic statements to his students". During class, he would describe Jews as a people of profound evil who had "created the Holocaust to gain sympathy." He also tested his students in exams on his theories and opinion of Jews.