It is not only about the quality of the workplaces and education which is available there. You should also keep in mind the minimum wage there in the United States is significantly higher when compared to the rest of the continent. Actually, there are only a handful of countries in the world which have higher salaries to those we can find in the United States.
That is why so many people are willing to move there, either legally or illegaly.
Lately, people from Venezuela have been the lastest nationals who have chosen to move there in significant numbers. Minimum wage in Venezuela is about 30$-40$ per month, for those who work within the public sector, while in USA one could get a job with a pay rate at 10$/hour. That is the main factor which drives people to move there and send money back to their family members in Venezuela.
On the racial struggle of people there: it has been well documented and studied. Fortunately, it would seem it is not longer as tolerated nowadays to be blatantly racist as in the past.