As it continues through Santa Clara County, it meets numerous local roads before interchanging with the Montague Expressway.
The highway crosses under an overpass at Middle Road before interchanging with Route 401, the freeway's final spur, at another partial cloverleaf interchange.
Continuing through mountainous areas, it cuts through Hickory Run State Park before interchanging with Interstate 80 and Pennsylvania Route 940 just to the north of the state park.
PA 997 continues to the northwest, intersecting with PA 533 and PA 641 (in Roxbury) before interchanging with Interstate 76 in Newburg at Exit 201.
Closely paralleling Devil's Foot Road, Route 403 continues eastward before interchanging with U.S. Route 1 (Post Road) and Davisville Road; the two roads are served via a single exit.
The road crosses the Cooper River into Collingswood, running to the east of Harleigh Cemetery before interchanging with CR 561 and passing under the PATCO Speedline.
The two routes head through commercial areas on the outskirts of Westminster, passing by the TownMall of Westminster before interchanging with MD 27 (Manchester Road) at a folded-diamond interchange.
It passes through residential and commercial areas of Rutherford, intersecting County Route 32 (Meadow Road) before crossing into East Rutherford, where it intersects County Route S32 (Union Avenue) before interchanging with State Route 120 and County Route 120 (Paterson Plank Road).
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 before interchanging with Interstate 280.
The freeway crosses Jefferson Boulevard and Amtrak's Northeast Corridor railroad on twin-span bridges and passes to the north of the Lincoln Park Cemetery before interchanging with US 1 at exits 5A-B.
Significantly, what happened before this interchange?
