Why might Uncle Hammer’s crossing the bridge and allowing people in the other car to think he is Mr. Granger negatively affect the Logans in the future

Uncle Hammer and his Packard provides a marked parallel to Mr. Granger. On the surface level, Hammer provides a means for Cassie to see the possibilities available to black men beyond becoming farmers and workingmen like Papa and Mr. Morrison. The Packard is a mark of status, which symbolizes that Uncle Hammer is just as good as, or even better than any white man. Mama says that this will comeback to haunt them because the white people crossing the bridge will have realized that the Packard is being driven by a black man who did not yield to their "right of way".

The fact that Uncle Hammer takes it upon himself to speed pass the Wallace's car is a brave thing to do. It is considered proper for black travelers on the bridge to give white travelers the right of way. The only reason the Wallace's tip their hats at the passing car is because they think it belongs to the Grangers. Mama knows that evntually they will have to pay for the breach of etiquette.