becasue we had a civil war over it. We nearly had a civil war over immigration during the depression. We nearly had a civil war in the 60’s over it. And we’re very close to having a civil war over it today.

Why? PEOPLE VOTE BY RACE

https://www.quora.com/Why-do-Americans-love-classifying-their-people-based-on-their-race-Why-dont-they-just-coexist-without-minding-ones-race-at-all