Father/Son, Mother/Daughter
Throughout the film we see that the relationship between father and son and mother and daughter is strained. Sam and Buddy's relationship is one we only experience the indirect nature of as Buddy has passed on, but we feel the strain in it and begin to see why. Sam and Pilar's love has been banned by their parents, and thus we begin to understand the relationship between Pilar and her mother is similar. This strained relationship permeates throughout the characters in the film and we see how unresolved issues between parent and child are passed on as we see Del and his son have a strained relationship as a result of Del not knowing his father. Sayles shows us that in every culture there are issues with children and their parents and how it greatly affects people's lives.
Buried History
The film begins with a skeleton being unearthed in the desert. This image is a perfect picture of one of the themes of the story which is unearthing the past that has been buried. As the story progresses we see that everyone's story relates to the skeleton of Charlie Wade. Charlie was running the county he was meant to serve as if he owned every last inch of it. He served his own brand of justice which was to kill anyone who didn't pay him. We find out that his ways ruined the lives of every character in the story. So when Hollis kills his sheriff, Buddy and Otis keep the truth buried for years in order to protect the people in the town. When it finally comes out Sam decides to keep it buried as he finds that it wasn't his father who killed Charlie. And the biggest buried truth is that Sam and Pilar are half brother and sister once they discover that their parents had been lovers.
Race
This film has a deep current of race that runs through it. Texas is the setting where the racial tension continues to run high. We watch as Charlie demoralizes Otis in his bar, and kills Eladio in the middle of the road. Charlie believes that he is the dominant one to everyone he comes in contact with no matter their race. His racism is equally horrible and comes with a great price as he is the law in the town. We also watch as Sam and Pilar's journey unfolds in the story to reveal that they have been kept apart their entire lives which they believe is because of their race and their parents prejudice. When the truth is revealed we see that they would rather allow everyone to believe they are racists than to allow their adultery to become known in the town thus they further the racial tension amongst those in the community.