Stratified United States

If the U.S. is highly stratified on the basis of race, how do we explain the success of people such as Oprah Winfrey and Condoleezza Rice? Identify other highly successful people who have overcome racial challenges.
I believe there is an explanation to the success of people in a highly stratified United States.   I believe there is a bigger picture to be looked at when explaining these circumstances.   If you took a step back and looked at the broader picture of society and its strata you could then see a clearer image.   Take Alexander Twilight for instance, he was born during very trying times in the United States.   During his time Slavery had become a big issue in the United States since the signing of the Declaration of Independence.   It seemed to the North that it was contradictory to what the colonies had fought for and won from Great Britain, Independence.  
Another highly successful person to have overcome racial challenges was an African American by the name of Alexander Twilight, who was alive during the second period of American slavery.   Alexander Twilight in which was born in Corinth, Vermont on September 26, 1795 and died on June 19, 1857 became the first African American to earn a bachelor’s degree.   Alexander became licensed as a congregational preacher after becoming an educator, minister, and politician.   Alexander eventually became a principal of the Orleans County Grammar school where he built the Athenian Hall in the State of Vermont.   In 1836 Alexander Twilight became the first African American to become elected to public office as a state legislator.  
With the image of Alexander Twilight and the image of the United States in the times after the revolutionary war and before the civil war, you can ultimately explain the success of persons in a highly stratified United States.   When I was growing up I was always told it is not only what wisdom you have to climb a mountain in life it is also how you use the wisdom to climb that mountain and...