Map of the Lower Hudson Valley with NY 100 highlighted in red
|Maintained by NYSDOT and Westchester County|
|Length:||33.27 mi (53.54 km)|
|Existed:||1930 – present|
|South end:||Cross County Parkway in Yonkers|
| I-287 in Greenburgh
Saw Mill River Parkway in Mount Pleasant
Taconic Parkway in New Castle
|North end:||US 202 in Somers|
New York State Route 100 (NY 100) is a major north–south state highway in Westchester County, New York, in the United States. It begins parallel to Interstate 87 (I-87) at a junction with the Cross County Parkway in the city of Yonkers and runs through most of the length of the county via the city of White Plains up to U.S. Route 202 (US 202) in the town of Somers just south of the county line with Putnam County. NY 100 was designated as part of the 1930 renumbering of state highways in New York. Prior to becoming a state road, various sections of NY 100 were part of several important early roads in the county.
Route description 
NY 100 begins in the city of Yonkers as Central Park Avenue (also known as Central Avenue) at exit 4 of the New York State Thruway (I-87). This portion of Central Park Avenue is maintained by Westchester County as County Route 47II (CR 47II), an unsigned route. Central Park Avenue continues south into the Bronx and serves as a frontage road for I-87 in this area. NY 100 diverges from I-87 just north of exit 5 and heads northeast, crossing over the Sprain Brook Parkway about 0.6-mile (1.0 km) beyond the split. Central Park Avenue continues out of the city of Yonkers in the area between the Grassy Sprain Reservoir and the Bronx River into the town of Greenburgh. NY 100 runs through the hamlet of Hartsdale, about two miles (3 km) north of the city line, and where the loop route NY 100A (Hartsdale Avenue) begins. Central Park Avenue then enters the city limits of White Plains, where the road ends at NY 119 (Tarrytown Road). Within White Plains, the road is county-maintained with unsigned designations of CR 99 and CR 90.
NY 100 north follows NY 119 west for a 0.5-mile (0.8 km) overlap through the town center of Greenburgh. Access to I-287 (the Cross-Westchester Expressway) and the Bronx River Parkway can be made in the vicinity of the 100/119 overlap. NY 100 then splits off to the north using Hillside Avenue and Grasslands Road as it goes around the perimeter of Westchester Community College. At a four-way intersection between Grasslands Road, Knollwood Road, and Bradhurst Avenue, NY 100 meets with the north end of NY 100A (Knollwood Road) and the east end of NY 100C. NY 100 makes a right-hand turn to follow Bradhurst Avenue north from the junction while Grasslands Road continues west as NY 100C. Bradhurst Avenue leads into the hamlet of Hawthorne within the town of Mount Pleasant, crossing over the Sprain Brook Parkway along the way. NY 100 subsequently shifts onto Saw Mill River Road (NY 9A) using a brief section of NY 141 (Broadway). From this junction, Saw Mill River Road (carrying 9A and 100) is a partially controlled-access highway as it continues north alongside the Taconic State Parkway. It has a grade-separated junction with NY 117 (Bedford Road) about 1.1 miles (1.8 km) north of the 9A/100 merge. 9A and 100 then enter the eastern edge of the village of Briarcliff Manor.
NY 100 then branches off on its own again in Briarcliff Manor, with NY 9A continuing north along the Briarcliff–Peekskill Parkway and NY 100 continuing northeast on the Saw Mill River Road, which roughly follows New York Central's old Putnam Division railroad. Many of the railroad's old stations can still be found along the highway. NY 100 passes through New Castle and meets NY 133 in the hamlet of Millwood, where access to the Taconic State Parkway can also be made. From here, NY 100 then follows the path of the Croton Turnpike (alternatively known in the area as Somerstown Turnpike and also as Saw Mill River Road). The road continues into the town of Yorktown, passing by the hamlet of Kitchawan. NY 100 then crosses the Croton Reservoir on Pines Bridge. After crossing the reservoir, NY 118 splits off to the west on Saw Mill River Road, while NY 100 continues northeast on the Croton Turnpike.
The Croton Turnpike continues into the town of Somers, passing by some of the last remaining rural areas in Westchester County, including Muscoot Farm, a county owned early-1900's interpretive farm. North of the farm NY 100 intersects with NY 35 in the hamlet of Whitehall Corners, where a Pepsi Cola plant is located. In its northern extremes, NY 100 roughly parallels the Croton Reservoir on the north side before meeting up with US 202 in the hamlet of Somers, where it ends opposite the Elephant Hotel.
Early roads 
The southernmost section of NY 100, known as "Central Park Avenue", appeared in maps by 1888. It was constructed as a plank road in 1874 connecting Macombs Dam Bridge (then known as Central Bridge) to Westchester County. The road continues south into the Bronx as Jerome Avenue, which was originally also called Central Park Avenue.
The middle section of NY 100 uses the Saw Mill River Road, an early colonial road connecting many different hamlets and villages in Westchester County. It follows along the path of various rivers and brooks as it winds its way to the north of the county. The road is now used as parts of several state routes, including NY 9A, NY 100, and NY 118. The section used by NY 100 follows the path of the Pocantico River between the hamlets of Hawthorne and Millwood.
The northernmost section of NY 100 runs along a part of the "Croton Turnpike", an early private toll road that was chartered in 1807. The Croton Turnpike connects the village of Ossining (then called Sing Sing) to the hamlet of Somers via Kitchawan. The road was made free in 1849. The Saw Mill River Road was rerouted to overlap the Croton Turnpike as it navigates around and across the Croton Reservoir, which was constructed between 1837 and 1842.
In 1908, the New York State Legislature created Route 2, an unsigned legislative route extending from the New York City line at Yonkers to the Columbia County village of Valatie. Route 2 followed Central Park Avenue (mostly now NY 100) north through Yonkers to Hartsdale, where it veered west to bypass White Plains on modern NY 100A, NY 100B, and NY 119. It rejoined what is now NY 100 at the junction of Tarrytown Road (NY 119) and Hillside Avenue and followed it north along Hillside Avenue and Grasslands Road to the modern junction of NY 100, NY 100A, and NY 100C, at which point Route 2 continued west toward the Hudson River on current NY 100C.
NY 100 was first designated in the 1930 renumbering of state highways in New York, when many of the state roads in Westchester County were first publicly posted with route numbers. Originally, it went north from the Croton Reservoir to US 6 (now NY 6N) in Mahopac Falls on what is now NY 118, Baldwin Place Road, and Myrtle Avenue. Also assigned at this time was NY 118, which began adjacent to the Croton Reservoir at NY 100 and proceeded northeast along the Croton Turnpike to NY 22 in Croton Falls via modern NY 100 and US 202. The alignments of NY 100 and NY 118 north of the Croton Reservoir were swapped c. 1939, placing NY 118 on the more westerly alignment and NY 100 on the Croton Turnpike between the reservoir and Croton Falls.
In December 1934, at the insistence of the Automobile Club of New York, several numbered routes were extended and signed within New York City, with NY 100 being one of these routes. NY 100 was extended south from the Yonkers line in the Bronx along Jerome Avenue to the Grand Concourse. NY 100 crossed into Manhattan via East 149th Street and the 145th Street Bridge. In Manhattan, NY 100 continued south along Lenox Avenue, 110th Street, Fifth Avenue, 96th Street, and Park Avenue, ending at Houston Street (NY 1A). South of Fordham Road, NY 100 was overlapped with NY 22 all the way to Houston Street. The NY 100 designation was removed from New York City following the opening of the Major Deegan Expressway in 1956.
In 1934, US 202 was designated and overlapped with NY 118 (later NY 100) from Somers to Croton Falls. The overlap between NY 100 and US 202 lasted as late as 1990. NY 100 was cut back to end at US 202 in Somers by 2004. The south end of NY 100 had been at the New York City line since 1956; however, as of 2007, NYSDOT recognizes the Cross County Parkway underpass as the official southern terminus of NY 100.
Expressway plans 
In April 1956, the Westchester County Planning Commission recommended that a new expressway should be built along the current NY 100 north of White Plains. The road was to be an extension of the Central Corridor Expressway, which was proposed as NY 125. This 21-mile (34 km) extension was stretch to Putnam County. The area was a high-priority corridor, stretching from the Cross-Westchester Expressway (I-287) to the proposed Northern Westchester Expressway (NY 35). North of NY 35, the area was a medium-priority corridor, ending at US 6 in Mahopac. This plan was not implemented.
Suffixed routes 
- NY 100A (4.21 miles or 6.78 kilometres) is an alternate route of NY 100 through Greenburgh. It was assigned as part of the 1930 renumbering of state highways in New York.
- NY 100B (2.88 miles or 4.63 kilometres) is a spur off NY 119 in Greenburgh. Although the route does not intersect NY 100, it meets NY 100A and terminates at NY 119 roughly 200 yards (180 m) from where NY 119 meets NY 100. The route was assigned in the late 1930s.
- NY 100C (1.24 miles or 2.00 kilometres) is a spur off NY 100 in Greenburgh and Mount Pleasant. It was assigned in the late 1930s.
Major intersections 
The entire route is in Westchester County.
|Yonkers||0.00||0.00||Cross County Parkway to Bronx River Parkway||Exit 4 (Cross County Parkway)|
|I-87 / Thruway||Exit 5 (I-87 / Thruway)|
|1.11||1.79||Sprain Brook Parkway||No access from NY 100 north to Sprain Brook Parkway south|
|Greenburgh||6.89||11.09||NY 100A (West Hartsdale Avenue)||Hamlet of Hartsdale; southern terminus of NY 100A|
|White Plains||8.61||13.86||NY 119 east (Tarrytown Road)||Eastern terminus of NY 100 / NY 119 overlap|
|Greenburgh||I-287 (Cross-Westchester Expressway)||Exit 5 (I-287)|
|9.10||14.65||NY 119 west (Tarrytown Road)||Western terminus of NY 100 / NY 119 overlap|
|12.26||19.73||NY 100A (Knollwood Road) / NY 100C (Grasslands Road)||Northern terminus of NY 100A; eastern terminus of NY 100C|
|Mount Pleasant||13.67||22.00||Sprain Brook Parkway to Taconic Parkway / Saw Mill River Parkway|
|14.85||23.90||NY 141||Hamlet of Hawthorne|
|15.02||24.17||NY 9A south (Saw Mill River Road)||Southern terminus of NY 9A / NY 100 overlap|
|Taconic Parkway south||Southbound exit and northbound entrance|
|18.13||29.18||NY 9A north||Northern terminus of NY 9A / NY 100 overlap|
|New Castle||20.71||33.33||NY 133 west||Southern terminus of NY 100 / NY 133 overlap|
|20.85||33.55||Taconic Parkway||Hamlet of Millwood|
|21.10||33.96||NY 133 east||Northern terminus of NY 100 / NY 133 overlap|
|21.56||34.70||NY 120||Western terminus of NY 120|
|Yorktown||23.23||37.39||NY 134||Hamlet of Kitchawan|
|24.94||40.14||NY 118||Southern terminus of NY 118|
|Somers||29.30||47.15||NY 35||Hamlet of Whitehall Corners|
|29.88||48.09||NY 139||Southern terminus of NY 139|
|32.35||52.06||NY 138||Western terminus of NY 138|
|33.27||53.54||US 202||Hamlet of Somers|
See also 
- Standard Oil Company of New York (1930). Road Map of New York (Map). Cartography by General Drafting.
- "2008 Traffic Volume Report for New York State" (PDF). New York State Department of Transportation. June 16, 2009. pp. 156–157. Retrieved January 30, 2010.
- Westchester County Department of Planning (February 2010) (PDF). County and State Roads and Parks (Map). http://www.westchestergov.com/planningdocs/pdfmaps/countystateroadsparks.pdf. Retrieved March 31, 2010.
- I Love New York (2007). 1977–2007 I Love New York State Map (Map).
- McNamara, John (1996). History in Asphalt: The Origin of Bronx Street and Place Names (3rd ed.). The Bronx County Historical Society. p. 116. ISBN 978-0-941980-16-6. Retrieved March 31, 2010.
- "On old Saw Mill River Road". The New York Times. July 19, 1914. p. X1.
- Journal of the Assembly of the State of New York. 1835. – lists an 1835 amendment to "An act to incorporate the Croton Turnpike company, passed April 6th, 1807"
- Journal of the Assembly of the State of New York. New York State Assembly. 1849. – lists the act to repeal the charter of the turnpike
- "History of Westchester". Westchester County. Retrieved May 16, 2008.
- State of New York Department of Highways (1909). The Highway Law. Albany, NY: J. B. Lyon Company. pp. 53–54. Retrieved June 6, 2010.
- New York State Department of Highways (1920). Report of the State Commissioner of Highways. Albany, NY: J. B. Lyon Company. pp. 497–498. Retrieved June 6, 2010.
- Standard Oil Company of New York (1929). New York in Soconyland (Map). Cartography by General Drafting.
- Esso (1938). New York Road Map for 1938 (Map). Cartography by General Drafting.
- Standard Oil Company (1939). New York (Map). Cartography by General Drafting.
- "Mark Ways in the City". The New York Times. December 16, 1934. p. XX12.
- Anderson, Steve. "State and US Roads in New York City". NYCRoads. Retrieved March 31, 2010.
- Weingroff, Richard (January 9, 2009). "U.S. 202 – Maine to Delaware". Highway History. Federal Highway Administration. Retrieved March 31, 2010.
- New York State Department of Transportation (1990). Croton Falls Digital Raster Quadrangle (Map). 1:24,000. http://gis.ny.gov/gisdata/quads/drg24/dotpreview/index.cfm?code=dd49. Retrieved March 31, 2010.
- New York State Department of Transportation (October 2004). Official Description of Highway Touring Routes, Scenic Byways, & Bicycle Routes in New York State (PDF). Retrieved July 17, 2009.
- "2007 Traffic Volume Report for New York State" (PDF). New York State Department of Transportation. July 25, 2008. p. 155. Retrieved January 30, 2010.
- Anderson, Steve. "NY 100/125 – Central Corridor Expressway (unbuilt)". NYCRoads. Retrieved November 22, 2007.
- Shell Oil Company (1937). Shell Road Map – New York (Map). Cartography by H.M. Gousha Company.
- Gulf Oil Company (1940). New York Info-Map (Map). Cartography by Rand McNally and Company.
|Wikimedia Commons has media related to: New York State Route 100|
A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.