The Heckscher State Parkway (formerly known as the Heckscher Spur) is an 8.24-mile (13.26 km) long parkway in the Suffolk County, Long Island, New York. The parkway, located entirely within the town of Islip, begins at exit 41A of the Southern State Parkway (doubling as the southern terminus of the Sagtikos State Parkway) in West Islip. The parkway proceeds east as a six-lane parkway through Brentwood, Central Islip and south through Islip Terrace and Great River. The eastern terminus of the parkway is at the toll barrier for Heckscher State Park in Great River, within exit 46. The Heckscher State Parkway comprises the eastern portion of New York State Route 908M (NY 908M), an unsigned reference route, with the Southern State Parkway occupying the western section. There is very little to indicate the actual existence of the parkway's name, as it is signed as an extension of the Southern State Parkway. Exceptions, however, are located along NY 27 and NY 27A.

The Heckscher State Parkway was first constructed from NY 27A to the entrance, when Heckscher (formerly Deer Range) State Park opened in 1929. In 1959, bids were announced for a new Heckscher State Parkway, costing $8,327,000 (1959 USD). The parkway was completed in 1962, and opened on November 3, with speeches by Robert Moses and governor Nelson Rockefeller. The parkway necessitated expansion of facilities at Heckscher State Park, including 18,000 feet (5,500 m) of new beachfront. The following October, the Long Island State Park Commission helped plant brand new trees and flowers along the parkway, including using evergreen trees to screen drivers from the neighborhoods on the side of the parkway. Under the Long Island Transportation Plan 2000, a study done in the late 1990s, the Heckscher would receive widening for a carpool and bus lane from the Southern State to exit 44, with NY 27.

The Heckscher State Parkway begins at exit 41A of the Southern State Parkway, which doubles as the southern terminus of the Sagtikos State Parkway in the hamlet of West Islip. The Heckscher crosses through the interchange, becoming an eastbound six-lane local parkway, crossing under Manatuck Boulevard into the Brentwood section of Islip. A short distance later, the Heckscher enters exit 42S–N, a cloverleaf interchange with County Route 13 (CR 13; Fifth Avenue) in Brentwood. Exit 42S going eastbound connects to CR 13 via a service road (Spur Drive South) while exit 42N going westbound connects to CR 13 via Spur Drive North. After the interchange, the parkway bends slightly southeastward, then evening eastward through Brentwood, remaining a six-lane parkway surrounded by dense woods.

Near East Forks Road, the Heckscher State Parkway bends northeast, crossing through Islip and under Brentwood Road. A wider median appears after Brentwood Road, as the parkway continues east. This median returns to normal length just before approaching the overpass for Commack Road, where the parkway leaves Brentwood. A short distance later in the Central Islip section, the parkway enters another cloverleaf interchange, exit 43S–N, which serves NY 111 (Islip Avenue). After the interchange, the parkway continues east through Central Islip, bending northeast soon after as a six-lane parkway. After crossing under CR 17 (Carleton Avenue), the eastbound Heckscher enters exit 43A, which is a single ramp to Spur Drive South that connects to CR 17. Westbound, this is similar, with a single ramp to Spur Drive North.

After exit 43A, the Heckscher State Parkway makes its bend to the south, crossing under Manhattan Boulevard in Central Islip. Just after a pedestrian bridge, the Heckscher enters another cloverleaf interchange, this time exit 44W–E, which serves NY 27 (Sunrise Highway). After crossing over the Sunrise Highway, the Heckscher State Parkway continues southbound, now in the Country Village section of Islip. A short distance later, the parkway crosses over Long Island Rail Road's Montauk Branch tracks west of the Great River station. After crossing over the tracks, the parkway parallels Bayard Cutting Arboretum State Park and crosses over CR 50 (Union Boulevard). Just after CR 50, the Heckscher enters exit 45E–W, a cloverleaf interchange which serves NY 27A (Montauk Highway).

After exit 45E, the Heckscher continues southward, now a four-lane parkway with divided median. Now in Great River, the parkway crosses between several residential neighborhoods on each side, bending southward into Country Village once again. After a short stint through East Islip, the parkway bends southwest into exit 46, which serves Timber Point Road. After this exit, the parkway passes a turnaround to the northbound lanes, and enters the tollbooth for Heckscher State Park, where the official parkway designation terminates. The right-of-way continues south of the toll barrier through Heckscher State Park, soon rounding back to the northbound lanes.

Heckscher State Park, formerly known as Deer Range State Park, began in 1925 with people who were opposing the Northern State Parkway because it would hurt their hunting of foxes in the area. Their legislators in the New York State Legislature refused to provide money for a park, so the group went to August Heckscher, a local philanthropist. He donated the $262,000 (1929 USD) to the Long Island State Park Commission (LISPC) and got land appropriated for a new park, which became Deer Range State Park. On June 2, 1929, the park was rededicated in the name of August Heckscher. Speaking was done by Alfred E. Smith, former governor of New York and Robert Moses, head of the LISPC along with Heckscher, who had a bronze tablet made honoring his work. August Heckscher died in April 1941, nearly twelve years after dedication of the park in his name.

The Heckscher State Parkway began as a two-lane from NY 27A to Heckscher State Park, constructed in 1929. No progress was made for extension for almost two decades, and when the extension of the Southern State Parkway opened in November 1949, provisions were left at the Bay Shore Road junction for where the Heckscher, Southern, Sagitkos and Captree Parkway (now the Robert Moses Causeway) would meet. In 1952, when the state acquired the W. Bayard Cutting estate in Great River, projections were to have the Heckscher constructed by 1954 so the land could be turned into an arboretum. In March 1959, bids were announced by the State of New York Department of Public Works to construct the last 6.27 miles (10.09 km) section of the Heckscher State Parkway from the Sagtikos State Parkway to NY 27A. This, along with a widening of the Southern State Parkway, would complete the gaps in the original 200-mile (320 km) parkway system proposed by Robert Moses. The estimated cost of construction totaled out to $8,327,000 (1959 USD) and with a slated completion 18 months later, September 1960.

On November 1, 1962, it was announced by the Long Island State Park Commission that the parkway would open on the upcoming Saturday (November 3) with attendance of Robert Moses and governor Nelson Rockefeller with a ceremony at 11:30 AM. On November 3, the Heckscher State Parkway's full alignment was opened to traffic, cutting a ribbon on a rainy morning. A motorcade of 110 vehicles followed the new parkway to the Bayard Cutting Arboretum, but Governor Rockfeller was late due to mechanical difficulties with his personal plane. The new parkway also necessitated expansion of facilities, which included 1,658 acres (671 ha) of land and 18,000 feet (5,500 m) of new beachfront. Opening the parkway also made connections to the nearby Southside Sportsmen's Club, which would be turned into a recreation area, and the Bayard Cutting Arboretum.

In 1963, the Heckscher State Parkway received a brand new set of trees planted along the parkway. The Long Island State Park Commission was to plant 67,000 trees, shrubs and ground cover on the new parkway (along with several other parkways on Long Island), which included evergeen trees, Japanese crab, cherry, mimosa, magnolia, forsythia and laurel plants were being planted. From 1997–2001, engineers at Parsons Brinckerhoff had been working on a $6.5 million (2001 USD) study that would expand that would improve Long Island's transportation system by 2020. Included within the plan was 130 miles (210 km) of road widening. These proposals would give the Heckscher a restricted-access lane for buses and carpooling drivers, part of a 60 miles (97 km) long system on Long Island. Under the proposal, called "Long Island Transportation Plan 2000", a lane would be added from exit 44, which serves NY 27, to the Southern State Parkway.

Exit numbers continue sequentially from those of the Southern State Parkway. The entire route is in Suffolk County.