The simple
Every citizen (and non-citizen) has different ways of thinking and not everyone shares the same opinion.
Long
Politically, someone may believe that government funding should go towards fixing the water in Flint, Michigan. Others may think the same funding should go towards a militia trained to fight in space. Someone may think threatening another country with nuclear warfare is a bad idea; others may think "nuke 'em!" (talking about you, Trump).
This division is why we have elections. Not everyone will agree on the same things. We as a people vote for what laws we want, what people we want having a say in enacting these laws, etc. In the end, majority wins on the decisions.
Racially is a little more difficult. Again, not everyone agrees on the same thing but this is more having to do with how someone was raised. Pre-civil rights, some caucasian Americans were taught that the other races were inferior to them. If this went uncorrected, they grew older and taught their young the same thing. It then starts a vicious cycle that can only be interrupted when one of them decides enough is enough; skin tone does not mean someone is less intelligent than I.
Racism is not exclusive to whites! I'll put it in bold for emphasis. I am African-American. My own grandfather (also black) can be racist at times towards Mexican, Native American, Indian, Middle Eastern, Chinese, etc. and even other black people! It was how he was raised; he believes outlandish things. Same with my grandmother on my dad's side. However, my mother/his daughter and my dad/her son did not adopt these same methods of thinking. They could've, but they didn't; they decided not to. Because of this, I do not share the same opinions with my elders.
Apply this same way of thinking to ALL of America. Some believe black people are still less than whites. Some believe America should build a wall between us and Mexico (news flash, still won't keep immigrants out). Some people have an irrational fear that all Middle Easterners are a threat.
It's all in the way we are individually raised and it is then up to youth of the next generation to right these ignorant wrongs and mend the racial division.
Hope this helps. That question is more complicated than it may seem on the surface and I do not want to write a whole dissertation over on your prompt as you probably wouldn't read it all anyway.
