The third piece, which creates the "burden of history" to Sam, was the fact that Pilar was his half-sister, and that his relationship with her should not be continued. Finally, the last piece of mystery was the assumption, or truth, that it was Buddy who did the crime against Charley. In the early part of the story, it was thought that the differences in race between Sam and Pilar was the reason why his father was disapproving of their relationship. Ironically, it was the "burden of history," so to speak. Also, the assumptions that Buddy killed Charley became a burden to Sam because it somehow haunted him that soon led him to search for the truth.

Tomas Sandoval also suggested in another way how history can create a burden depending on how the people create things out of what happened in the past. In the end of the film, it was discovered that it was not Buddy who killed Charley, but Deputy Hollis Pogue. Hollis killed Charley because he witnessed how Eladio was shot by Charley. Hollis did not want another similar case to happen to other people that's why he killed Charley. From this, Tomas suggest that

Once again we see how the film understands history. It is not a thing of the past but a created reality of the present. Just as the flashbacks in the film occur without a fade away or a break in the action, so too the past is tied to the...

This was particularly shown in the character of Charley Wade, who was described as a racist and unfair sheriff. However, despite of the racial differences, Tomas Sandoval indicated how the story had also shown that the borders were not barriers between people, but it was the people and from the history that they live with them that creates barriers between themselves.
The town of Frontera is also searching for its true self in the past. Frontera is a town where "nineteen out of twenty" people are Mexican and the rest are white or Black. Of course the town's power structure rests (at least for the moment) in the hands of the white minority. The history behind this present situation is repeating itself, only this time, the roles are reversed. Everyone in town knows that in the next elections, for the first time, the Mexican majority will assume its place in the city's government as they already have in the businesses, schools, and churches.

Bibliography

Sandoval, Tomas. The Burden of History and John Sayle's Lone Star.

http://bad.eserver.org/issues/1996/28/sandoval.html