The junction with the Merritt Parkway is currently the only single-point urban interchange (SPUI) in the entire state.

South of Route 15, Main Street continues for another 0.3 miles (0.48 km) to the Bridgeport line as an unsigned state highway with designation State Road 731 and provides access to Trumbull Mall.

It continues north, reaching its end at Route 34 in the Stevenson section of Monroe.

Operations of the turnpike continued through 1852 when the portion north of Monroe center was discontinued.

The continuation into Bridgeport, which would later become Route 25, was at the time part of State Highway 122.