At its north end, the short
PR-18 continues from north to south along PR-52 towards
Hato Rey and
Santurce. This short segment is known as , the only segment of the route still unofficially bearing this name, since PR-18 is now officially named . The combined route of PR-18 and PR-52 runs
concurrent with the unsigned
US Interstate Highway PRI-1. PR-52 continues southward along Cupey and Caimito, crossing the westernmost edge of the
Sierra de Luquillo in Trujillo Alto on the way to Caguas. In Caguas, it crosses the
Valley of Caguas, where it functions as a north-south
bypass for local traffic, before elevating south into the
Sierra de Cayey. Puerto Rico Highway 52.jpg|PR-52 south at its exit to PR-1 south in San Juan Autopista PR-52, salidas hacia la carretera PR-177, San Juan, Puerto Rico.jpg|PR-52 south approaching exits 1A-B to
PR-177 in San Juan Autopista PR-52, salida hacia la carretera PR-199, San Juan, Puerto Rico (1).jpg|Heading south in San Juan Autopista PR-52, salida hacia la carretera PR-199, San Juan, Puerto Rico (2).jpg|PR-52 south at exit 2 to
PR-199 in San Juan Autopista PR-52, Trujillo Alto, Puerto Rico (2).jpg|Heading south in Trujillo Alto Autopista PR-52, salida hacia la carretera PR-156, Caguas, Puerto Rico (1).jpg|Heading south in Caguas In Cayey, PR-52 passes extremely close to the municipality of
Cidra between approximately kilometer markers 34 and 30. In fact, Exit 32 to
Guavate is so close to the Cidra border that once the exit is taken and instead of going south to Guavate and
Patillas through
PR-184, going north it quickly ends at
PR-1 and a welcome sign to Cidra is shown. The tollway itself never enters Cidra itself, but PR-1 (the parallel road from Ponce to San Juan) does. The speed limit is reduced in the section between Cayey and Salinas crosses the
Sierra de Cayey, resulting in a more curvy and hilly section than the other sections of the highway. Located at the orographic lift of the
Cordillera Central, it also experiences more fog and lower visibility than the rest of the road due to the altitude. This is also the highest point of the route. One of Puerto Rico's only 2
rest areas is located on this section of the expressway in Salinas. (map) The other rest area is located on
PR-53 (northbound only) near
Humacao/
Naguabo municipality border and, just like the rest area on PR-52, it has no operating facilities. (map) The rest area does provide view of a pair of important landmarks, the
Monumento al Jíbaro Puertorriqueño and the famous
Tetas de Cayey. Beginning at the leeward side of Salinas, between here and Ponce, PR-52 crosses the southern coastal plain of Puerto Rico, crossing Santa Isabel and Juana Díaz. The route finally enters the urban area of Ponce at
barrio Sabanetas, marked by the famous
Letras de Ponce landmark. PR-52, Cayey (2025).jpg|Heading southwest in Cayey Cayey landscape from PR-52.JPG|View from PR-52 in Cayey Mon al jibaro2.JPG|The Monumento al Jíbaro Puertorriqueño and Las Tetas de Cayey PR-52 at Salinas (2025)-1.jpg|Heading southwest in Salinas Tacoma pick-up on PR-52, with water and flag, after Hurricane Maria, Puerto Rico.jpg|A
Toyota Tacoma pick-up truck on PR-52 south, with water and flag, after
Hurricane Maria (2017) Autopista PR-52, Santa Isabel, Puerto Rico (3).jpg|Heading northwest in Santa Isabel Letras de PONCE, PR-52 southbound, Barrio Sabanetas, Ponce, Puerto Rico, looking southwest (DSC05090Z).jpg|Heading west in Ponce
Express lanes In 2021, the
Puerto Rico Department of Transportation and Public Works and the
Puerto Rico Highways and Transportation Authority inaugurated express lanes with dynamic tolling (DTL) between San Juan and Caguas to help alleviate traffic congestion during peak hours. These
reversible lanes extends from PR-18, near Río Piedras Medical Center, to the Caguas Norte Toll Plaza with a variable rate between $0.50 and $6.00 per direction. The speed limit on the nearly 14-kilometer route ranges between 50 and 55 miles per hour (80–90 km/h). It is expected that in the long term the lanes will be extended to
PR-30 heading to
Gurabo. ==History==