Crossing northwest through the residential section of Sand Lake on Miller Hill, NY 66 soon leaves the town of Sand Lake for the town of Poestenkill. Along this northwestern stretch, NY 66 drops the Miller Hill Road moniker, crossing a junction with NY 351 (Reichards Lake Road / Round Top Road). A short distance after NY 351, the route returns to the rural nature it once had, crossing a junction with CR 68 (Snyders Corner Road). Winding northwest past a large quarry, NY 66 reaches the western terminus of NY 355 as it enters the town of North Greenbush. Now known as Main Avenue, NY 66 crosses into the hamlet of Wynantskill.