From an AP report (linked here at the Huffington Post):
The percentage of African-Americans earning STEM degrees has fallen during the last decade. It may seem far-fetched for an undereducated black population to aspire to become chemists or computer scientists, but the door is wide open, colleges say, and the shortfall has created opportunities for those who choose this path.
STEM barriers are not unique to black people. The United States does not produce as high a proportion of white engineers, scientists and mathematicians as it used to. Women and Latinos also lag behind white men.
Yet the situation is most acute for African-Americans.