[6] This highway consists of one lane in each direction for most of its length between Morovis and Toa Alta.

In Morovis, PR-159 travels from its intersection with PR-155 and PR-6623 in downtown to the Corozal municipal limit, crossing through Monte Llano and Unibón barrios.

[9] Through downtown Corozal, the route was replaced by PR-891, and PR-159 makes a bypass to evade the municipal center.

[10] Among the most important intersections are PR-137 (Expreso Ángel "Tony" Laureano), that heads to Vega Baja; PR-142 (Expreso de Corozal), that goes to Dorado; PR-155, the main highway between Vega Baja and Orocovis; PR-160, a route between Morovis and eastern Vega Baja; PR-164, the main highway to Naranjito, and PR-165, the main road between Toa Alta and Naranjito.

10 was the highway that led from Dorado to Coamo through Toa Alta, Corozal and Orocovis,[4][17][18] while Road No.