Guess all cities on US route 21. Only cities within the USA are counted. Towns, unincorporated areas, and other non-cites are not counted. Below the map, they will be listed with their states and counties in order of east to west along the road. If the county slot is blank, the city is in either multiple or no counties. Places where route 21 merges with interstates or other roads are counted.
While Route 21 passes through Virginia, it does not pass through any cities in that state, only towns.