- Western Terminus:
- Saw Mill River Road (NY 9A) in Elmsford
- Eastern Terminus:
- Bradhurst Avenue (NY 100) and Knollwood Road (NY 100A) in Valhalla
- 1.24 miles
Grasslands Road begins at a grade-separated interchange with Saw Mill River Road (NY 9A) in Elmsford. It runs east to Valhalla. There is an interchange with the Sprain Parkway. Immediately thereafter, NY 100C ends. Grasslands Road continues as NY 100 south. Bradhurst Avenue carries the NY 100 designation to the north. Knollwood Road (NY 100A) also terminates at this intersection.