Race and racism is of course a prevalent theme in this play, and is related very strongly to its title and the various and multiple "fences" that lie between different characters and the dreams that they try to achieve. Troy is a character who has experienced racism the hard way through his own lack of opportunities, in particular in his ability to play baseball professionally because when he was young they did not let black players play professional baseball. Note what he says about this in Act I scene 1:
I'm talking about if you could play ball then they ought to have let you play. Don't care what colour you were. Come telling me I come along too early. If you could play... then they ought to have let you play.
Troy points his finger at a system that excludes people not based on their talent or lack of it, but purely based on the colour of their skin. This has had a major impact on his life as a character, and in turn on his son, as the play explores.