major arteries or historical roads are exempt from the naming and numbering system. named streets with the designation "road," "pike," or "highway" instead of "street" usually predate the system and follow early winding routes. "boulevards" and "drives" are generally major thoroughfares with historic names. boulevards usually run east–west and drives, which were constructed on former trolley lines, run north–south but are designated as north and south only when they appear on both sides of arlington boulevard.