Zora Neale Hurston lived in a world where for the most part, whites dominated blacks and had much more societal power. This influence shows through in Their Eyes Were Watching God. OK, this post is about a theme, not author background, so I'll get on with it.
At least through chapter 10, white people are something of an unseen force in the novel. Nevertheless, the dominance of whites over blacks is an ubiquitous theme. On the first page of the novel, Hurston reeferences the "bossman", a presumably white power figure who controls the residents of Eatonville during the day. Eatonville itself was a novelty as the first all-black town in the U.S. This fact underscores the difficulty that blacks had in Hurston's time.
In the novel, not just being white but having white characteristics gives one power. Janie herself has white characteristics that give her something of an edge in the society of the time. Janie's mother was half white and was herself raped by a white man. Ironically, this disgusting display of white dominance instills some power in Janie. She is born with light skin and straight hair. Joe is attracted to her for this reason; he sees her as a way to display his own power because she has white traits. Because of these traits, she becomes an influential citizen of Eatonville.
Racism is always present in this novel. The characters struggle to gain indpendence, but are always held back by the fact that they are black, not white. Racism is not a good aspect of any society, but white dominance certainly is an important theme in the novel and in the society of Hurson's day