Racism against "mexicans"?

I am 16, persian-american, and attend a 95% white dominated publich high school in Northern VA (very rich-dominant white folks). I dont go a day without hearing racism against so called "mexicans" every single day. I sympathize very much for South Americans as well as all other immigrants, because I at least have the knowledge and posess the maturity to realize that these are people that want to better their lives, just as my parents did when they left Iran, and just as all other Americans' ancestors did. Why is it, then, that the highest cles of society, the rich white people, posess so much anger and hatred towards "mexicans"?? They are a very large workforce to the US economy, and have every right to retain their cultures within the US. Why are these whites so headstrong and stubborn; the clical American xenophobiac?? I not only hear racism from the kids in my school, but from these kids' PARENTS as well; its everywhere. Whats going on here?