- Western Terminus:
- Saw Mill Parkway and Nepperan Road in Hawthorne
- Eastern Terminus:
- Grasslands Road (NY 100C) and Saw Mill River Road (NY 9A) in Hawthorne
- 0.45 miles
Old Saw Mill River Road is a short extension of Grasslands Road (NY 100C) to the west for about half a mile in Hawthorne. It begins at Grasslands Road (NY 100C) near its interchange with Saw Mill River Road (NY 9A). It runs west as a four-lane road, mostly divided with a grass median. After about half a mile, it ends at an interchange with the Saw Mill Parkway, where it turns into Nepperan Road, a local street.