Puerto Rico Highway 181 (PR-181), also known as Expreso Trujillo Alto, is a road that connects the towns of San Juan, Puerto Rico in the north/northeast coast of Puerto Rico with Patillas in the southeast, passing through the municipalities of San Juan at Jesus de Piñero Avenue (PR-17) as it approaches the Teodoro Moscoso Bridge and the Luis Muñoz Marín International Airport, Trujillo Alto, Gurabo, San Lorenzo, Yabucoa and Patillas in the center of the town district near PR-3. Along with PR-10, PR-149, PR-1 and PR-52, it is one of the longest highways crossing the island from north to south through the central mountainous region. In the north part of Trujillo Alto it is a four-lane highway, turning completely rural on the way to Patillas with the exception of a small tract in Gurabo where it intersects PR-30.

Patillas is a beach town and municipality of Puerto Rico located in the southeastern coast, south of San Lorenzo; west of Yabucoa and Maunabo; and east of Guayama and Arroyo. It is spread over 15 barrios and Patillas Pueblo. It is part of the Guayama Metropolitan Statistical Area.