 County Route 508 splits from Route 21 by heading east on Bridge Street, crossing the Passaic River, and Route 21 continues north, passing by Bears & Eagles Riverfront Stadium.After passing under NJ Transit's Montclair-Boonton Line/Morris & Essex Lines and interchanging with Interstate 280, the route intersects County Route 506 Spur (Clay Street).Past the intersection with 3rd Avenue, Route 21 becomes a six-lane freeway.