New York State Route 231

NY 231 begins at an intersection with NY 27A (Montauk Highway) in the Incorporated Village of Babylon. From there, the route progresses northward around Hawleys Lake as a four-lane freeway. A short distance north of NY 27A, NY 231 meets ramps from County Route 50 (John Street), but only provides service to the county road from the southbound direction.

After John Street, the expressway crosses over the Long Island Rail Road's Montauk Branch, and thence continues northward through a large residential district. After paralleling Madison Street in North Babylon, NY 231 reaches a full cloverleaf interchange with NY 27 (Sunrise Highway).

From NY 27, NY 231 heads northward and northwestward, intersecting with Hunter Avenue in North Babylon, where the expressway portion ends and the highway becomes an arterial boulevard. The route curves back to the north through the large commercial district, interchanging with CR 34 (Deer Park Avenue). Just north of its interchange with CR 34, NY 231 reaches a full cloverleaf interchange with the Southern State Parkway, still in North Babylon.[6]

From its interchange with the Southern State Parkway, NY 231 continues northward as an arterial boulevard named Deer Park Avenue. The surroundings are mostly commercial, continuing as a four-lane road and intersecting with CR 4 (Commack Road) at a fork. After Commack Road, NY 231 becomes a residential arterial with a grassy, divided median and intersecting with CR 57 (Bay Shore Road) in Deer Park. The highway continues northward through Deer Park, crossing through a large commercial strip and underneath the Long Island Rail Road's Ronkonkoma Branch. There is a short interchange with Long Island Avenue in Deer Park, from which point NY 231 continues north and into Dix Hills, where it once again becomes residential near the intersection with CR 2 (Straight Path).[6]

The arterial road remains residential, continuing northward to an interchange with Interstate 495 (the Long Island Expressway) in Dix Hills. Here, the road widens to five lanes and crosses underneath the interstate, at which point NY 231 once again becomes four lanes. NY 231 then continues northward along the residential strip, intersecting with CR 67 (the Long Island Motor Parkway). The road then continues northwards, soon reaching a partial cloverleaf interchange with the Northern State Parkway, where the NY 231 designation terminates.

At its northern terminus, Deer Park Avenue forks into two Suffolk County-maintained routes; the western fork continues northwest as CR 35 (Deer Park Road, and later, Park Avenue), and the eastern fork continues northeast as CR 66 (East Deer Park Road).[6]

As suggested by its name, the Babylon–Northport Expressway was originally intended to be a north–south expressway spanning most of the width of Long Island, between NY 27A in the Incorporated Village of Babylon at its southern end and the intersection of Elwood Road, Fort Salonga Road (NY 25A), and Reservoir Avenue at its northern end, in the Incorporated Village of Northport.[9] Local opposition to the expressway, however, eventually resulted in the cancellation of the project before anything more than the existing 2 mile stretch could be constructed.[5] Despite this, roughly 40 percent of the properties along the proposed expressway's right-of-way were acquired by New York State for the unbuilt extension – including several properties along Elwood Road, in Elwood and Greenlawn.[9]

In 1962, the New York State Department of Public Works announced that Deer Park Avenue would be widened for a fourteen-mile stretch from Montauk Highway and NY 25A. The road would be expanded from a two-lane boulevard to a four-lane boulevard, at a cost of about $20 million (1962 USD) with a slated completion of 1970. The first section would have its contract let on May 3, 1962, with a cost of $2.4 million. This stretch would include the piece between the Southern State Parkway and Lake Avenue in Deer Park. The new piece of the right-of-way would be completed by the middle of 1965, in which a new road would be constructed along the 2-mile (3.2 km) section from the Montauk Highway to the Southern State Parkway.[8]

In the 1960s, the portion of CR 35 between the Southern and Northern State Parkways was transferred to the state of New York,[2] which designated the highway as NY 231.[3] Initially, NY 231 followed Deer Park Avenue (now CR 34) south to NY 27A in Babylon;[10] however, it was realigned c. 1969 to follow the 2-mile (3.2 km), limited-access section of the new Babylon–Northport Expressway.[10][11]