Montauk Highway is an east–west road extending for 95 miles (153 km) across the southern shore of Long Island in Suffolk County, New York, in the United States.

It heads east along the southern shore of Long Island, carrying NY 27A from Amityville to Great River.

In addition to being called Montauk Highway and Main Street in Suffolk County, it is also historically known as South Country Road, a name that is only used by former segments today.

The segment east of Station Road in North Bellport and CR 36 in Brookhaven still contains old concrete pavement, a common practice of the mid-20th century.

CR 80 ends west of the village of Southampton at Knoll Road, at which point Montauk Highway becomes state-maintained again as NY 900W, an unsigned reference route.

Montauk Highway was routed in a southeasterly direction toward the Atlantic Ocean coastline of Long Island, turning in an east-northeasterly direction in current Nassau County to more or less parallel the shore through Suffolk County, ending at Montauk Point, the easternmost point of land on the South Fork of the island.

As an all-weather road, Montauk Highway has rarely been breached by even serious storms; however, portions in the Hamptons were flooded out by the New England Hurricane of 1938.

[4][5] From East Patchogue to Brookhaven, NY 27 followed South Country Road instead, which was part of Montauk Highway at the time.

[7] On February 24, 1930, South Country Road was added to the Suffolk County highway system as CR 36.

[8] NY 27 and Montauk Highway were realigned to directly connect East Patchogue and Brookhaven via North Bellport.

[19] Ownership and maintenance of Montauk Highway between Great River and the town of Southampton was gradually transferred from the state of New York to Suffolk County during the 1960s and 1970s.

A 2.85-mile (4.59 km) section of Montauk Highway between Knoll Road to the west village line of Southampton at Tuckahoe Lane was retained by the state of New York and designated NY 900W, an unsigned reference route.