Complex sentence: Route 21 continues to the north and resumes along the west bank of the Passaic River, narrowing to four lanes and crossing back into Clifton at 13.22 miles and coming to an interchange with Ackerman Avenue at mile marker 13.52.
Split into simpler sentences: Route 21 continues to the north and resumes along the west bank of the Passaic River, narrowing to four lanes and crossing back into Clifton at 13.22 miles. Upon entering Clifton, the route comes to an interchange with Ackerman Avenue at mile marker 13.52.