What can a person do to break down racial barriers?

The U.S. looks alot better than it did a hundred years ago concerning matters of race. However, I don't believe that this progress in any way indicates that racism will ever go away. I'd guess that racism has existed for about as as long as race has existed. And so it will continue.

I'm obviously no expert but it seems to me that there is a more primal element at work where race is just one of any (sex, sexual preference, religion, age, financial status, education, weight, atractiveness, political affiliation, ...) falacious reasonings for not liking someone - or a group of someones.

You could teach someone to not be prejudiced about as well as you could teach someone to not be republican.

Ignorance breeds contempt.
If people get to know each other, they generally see they have more in common than differences. It's only when people see themselves in another that they learn to see that the barriers of colour, religion and culture as false walls. We are all humans. Period. Some are good and some are bad.