The following highways are numbered 100C:
Vermont Route 100 (VT 100) is a north–south state highway in Vermont in the United States. Running through the center of the state, it travels nearly the entire length of Vermont and is 216.666 miles (349 km) long. VT 100 is the state's longest numbered highway of any type.
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 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.
New York State Route 100C (NY 100C) is an east–west spur route of NY 100 located in Westchester County, New York, in the United States. The road is entirely within the town of Greenburgh, running for 1.24 miles (2.00 km) as Grasslands Road between an intersection with NY 9A to a junction with NY 100 and NY 100A. NY 100C has a junction with the Sprain Brook Parkway near its eastern terminus. The eastern terminus of NY 100C also serves as NY 100A's northern endpoint.
