Pat Garrett and Billy the Kid (1973)

In 1881 New Mexico, Pat Garrett, erstwhile traveling companion of the outlaw Billy the Kid, has become a sheriff, tasked by cattle interests with ridding the territory of Billy. After Billy escapes, Pat assembles a posse and chases him through the territory, culminating in a final confrontation at Fort Sumner, but is unaware of the full scope of the cattle interests' plans for the New West.