Using the "secondary" slider you can see the emergence of secondary centers of activity (there need not be three of them and they need not be equidistant from each other) creating new high-rent districts away from the center. Using "distance", you can adjust the distance away from the center at which these secondary peaks appear. Using "direction", you can model the direction, relative to the center, where these new high-rent districts appear. Finally, perhaps with the construction of an interstate bypass highway commonly known as a beltway, these "edge cities" agglomerate into a megalopolis ring. The controls are best operated in sequence and with "secondary" left in its extreme right position as the others are used.