Hector Street was the "unofficial" dividing line between the East End and the West End of town. The two sections of town represented the black community and the white community. People of a different race did not enter the other race's neighborhood. This was a simplistic view of life in segregated times. The whole point of the novel was to show the absurdity of segregation and how one boy unwittingly chose to end it. McNab's group knew better than to enter the black section of town designated by the side of Hector Street that one was on. Surely if one group invaded the other's territory there would be a huge fight. So, both groups would stand on opposite sides of the street and hurl insults at each other.