African Americans (also known as Black Americans and Afro-Americans) are an ethnic group in the United States. The first achievements by African Americans in various fields historically marked footholds, often leading to more widespread cultural change. The shorthand phrase for this is "breaking the color barrier".
One commonly cited example is that of Jackie Robinson, who was the first African American of the modern era to become a Major League Baseball player, ending 60 years of segregated Negro Leagues.