[2] With a length of 25.2 km (15.7 mi), it extends from the interchange of PR-10 and PR-14 located in Barrio Machuelo Arriba to the junction with PR-143 on the Ponce–Jayuya municipal limit.

[3] The road runs south to north through Barrio Machuelo Arriba, where serves as the main access to few communities and neighborhood developments before leaving the city of Ponce to the mountains.

Then, the road makes its way though the rural area, mostly alongside Río Cerrillos in barrio Maragüez, bordering the western bank of Lake Cerrillos until it reaches upstream of the reservoir, where it crosses the river for make its way along its eastern bank.

[4] Farther north, PR-139 climbs the mountains of the Cordillera Central through Barrio Anón until its terminus at the Ruta Panorámica.

[5] As the road is traveled in a northbound fashion, it serves barrios Machuelo Arriba, Maragüez, and Anón.