Remaining a mix of rural and residential, NY 156 winds east along server curves through Knox, soon crossing into the town of Guilderland. At the junction with Helderberg Avenue, the route turns north and bends around a long curve into the village of Altamont. Now known as Main Street, NY 156 turns south on Altamont Boulevard, while Main Street connects to NY 146 via NY 912C, an unsigned reference route. Along Altamont Boulevard, NY 156 runs as a two-lane residential street, paralleling a railroad line into the town of Guilderland, changing the monikers of Altamont–Vorheesville Road. Changing to a more rural roadway, NY 156, bending southeast through Guilderland.