In Troy's life, he has been stopped or "kept out" by many barriers. Identify one of those barriers. How has it stopped him?

In August Wilson’s Fences, Troy Maxson is a former Negro League baseball player who narrowly missed the opportunity to play in the Major Leagues. When he was a young player at the top of his game, Major League Baseball was segregated. The first African American baseball players were not recruited to the majors until Troy was already too old to be a viable team member. This experience leaves Troy cold and bitter, and it influences his relationship with his son, Cory, who has aspirations of playing college football.