Equality and difference (motif)
The speaker describes himself as equal in age and size to the Baltimorean. However, race sets them apart. While the speaker observes what is held in common between them, the Baltimorean child enforces the racial differences between them by using a slur against the speaker.
Baltimorean (symbol)
By describing the other little boy as a "Baltimorean," the speaker suggests he can stand in as a symbol for the city of Baltimore as a whole and its racist attitudes. Setting this "incident" in the north of the U.S. suggests that racism is not specific to the South. In fact, during the Civil War, a significant minority of people in Maryland were sympathetic to the pro-slavery Confederacy.
