Racism is not criminalized in this country, unless it involves criminal behavior. Saying something racist is usually free speech, though there are situations in which it is not.
The First Amendment basically protects political, public speech, not all speech. If you behave in a racist manner at your workplace, for example, your employer can fire you for it. You can suffer other consequences for racist speech and behavior that the First Amendment will not prevent. If you publish an article that says racist things about immigrants, you have a right to do that. But other people have a right to criticize you, refuse to associate with you, and do other things to express their disapproval of your views. You may therefore end up suffering in various ways for what you wrote, and the law will not protect you.
So, you're not a criminal if you say negative things about non-white people, and what you say may well be protected by the First Amendment, but that doesn't mean you can't experience negative consequences.