Education.
People need to believe justice is applied equally: white as well as black, rich as well as poor.
Close the extreme and growing wealth gap in the country.
Someone who is racist or fascist by definition rejects the notion that justice ought to be applied equally and just about anything else that you would likely consider moral or proper.
And fascism also is not a function of wealth inequality. Fascism has historically grown out of the middle-class. Seymour Martin Lipset identified fascism as "Extremismus der Mitte" in Germany. It's well at home in the petite bourgeoisie or in the US I guess you'd say the suburban middle class.