- Western Terminus:
- Main Street (NY 117) in Mount Kisco
- Eastern Terminus:
- High Ridge Road (NY 137) in Pound Ridge
- 8.89 miles
NY 172 is an east/west route from Mount Kisco to Pound Ridge. It begins at Main Street (NY 117) and runs east along South Bedford Road, which ends at Old Post Road (NY 22). NY 172 is multiplexed with NY 22 for about a mile along Old Post Road. Then, it splits off to become Pound Ridge Road, which continues east to Westchester Avenue (NY 137). The entire length is a two-lane undivided road.