The route passes north of Westerlo Town Park and intersects CR 412 (Airport Road) before leaving the hamlet on a winding, generally easterly alignment.

The route remains on an eastward track for another half-mile (0.8 km), meandering through dense woods before turning southeastward into an open area with a handful of isolated homes.

The conjoined routes connect two sections of CR 411 and pass over Hannacrois Creek before crossing into the town of Coeymans as Indian Fields Road.

Here, NY 143 meets the northern terminus of CR 111 as it turns to follow Hannacrois Creek eastward along the base of a narrow, winding valley.

[3] About 1.5 miles (2.4 km) from Alcove, NY 143 reaches the hamlet of Coeymans Hollow, a residential community at the route's junction with CR 103 (Blodgett Hill Road).

East of the community, the roadside homes give way to less developed areas of forests and fields as the highway intersects with CR 106 (Tompkins Road) in front of the Sycamore Country Club.

Here, NY 143 turns to the southeast, following Hannacrois Creek to the hamlet of Aquetuck, located about 1 mile (1.6 km) north of the Greene County line.

Here, the route turned to follow a northwesterly track through southern Albany County to the Delaware Turnpike (now part of NY 85) west of Westerlo.

[4] While most of the old plank road was retained as a state highway, the piece west of Westerlo was abandoned by 1926 in favor of a north–south connection between the hamlet and the Delaware Turnpike.