When Grace boards the train at the beginning of the film, she wears a white shawl over her shoulders while she says goodbye to her family from the door, but it's gone in the next scene as she enters the train car and is not seen when she debarks the train or during the cab ride home.
According to dates on some of the newspapers on which headlines track the progress of the mayoral campaign, it is happening in 1973. Baltimore's had a mayoral election in 1971 and the mayor's term is 4 years, so the next one was in 1975.