NY 100

New York State Route 100
Map of Westchester County in southeastern New York with NY 100 highlighted in red
Route information
Maintained by NYSDOT and Westchester County
Length:	33.27 mi (53.54 km)
Existed:	1930 – present
Major junctions
South end:	Cross County Parkway in Yonkers
	I-87 in Yonkers Sprain Brook Parkway in Yonkers I-287 in Greenburgh Sprain Brook Parkway in Hawthorne Saw Mill River Parkway in Mount Pleasant Taconic State Parkway in Millwood
North end:	US 202 in Somers
Location
Counties:	Westchester
Highway system
New York Highways Interstate U.S. State Reference Parkways ← NY 99 NY 100A →

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. 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.

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.