 In other cases, a primary Interstate highway passes around a city on one side, with a connecting loop Interstate bypassing the city on the other side, together forming a circumferential route, as with I-93 and I-495 in the area of Lawrence, Massachusetts.However, if a primary Interstate passes through a city and a loop bypasses it on only one side (as in the Wilmington, Delaware, area), no fully circumferential route is provided.Route numbering is challenging when a through highway and a loop bypass together form a circumferential ring road.