Puerto Rico Highway 18 (PR-18) is a freeway in Puerto Rico, which is also known as Expreso Las Américas. It runs from its north end at its intersection with PR-22 in San Juan to its south end in Río Piedras where it intersects with PR-1. At this point PR-18 becomes PR-52, known as Autopista Luis A. Ferré.
Puerto Rico Highway 3(PR-3) at nearly 100 miles long, is the second longest highway on Puerto Rico. It connects the San Juan neighborhood of Río Piedras to downtown Salinas indirectly around the eastern coast of the island. Highway 3 ranges from a three lane urban avenue in San Juan to a one lane rural road past Fajardo. While other roads connect San Juan, it runs the coastline of Puerto Rico east of San Juan, beginning in Río Piedras near Santurce and goes to Fajardo where it goes south paralleling the coastline to Humacao and Maunabo. It goes up to a mountain-scenic route and goes west to Salinas, where it meets PR-1.
Puerto Rico Highway 53 (PR-53) or unsigned Interstate PR3 is a main tollway that is parallel to Puerto Rico Highway 3, which goes from Fajardo to Salinas. Some segments are still in planning, but when finished it will be about 58 miles (93 km) in length. Two tunnels, about 0.6 mi (1 km) long each, in the towns of Yabucoa and Maunabo were completed in October 2008. It will connect the cities of Fajardo, Ceiba, Naguabo, Humacao, Yabucoa, Maunabo, Patillas, Arroyo, Guayama and Salinas, thus bordering the entire eastern and southeastern coasts of Puerto Rico. Its northern terminus is at PR-3 and PR-194 in Fajardo, and its south terminus is at PR-52 in Salinas.
Puerto Rico Highway 413 (PR-413) is a rural road located at the west point of Rincón, Puerto Rico and is famous in the island for being the main access to beaches near Tres Palmas and the Rincón Lighthouse, where local and international surfing tournaments take place. It is named the "Road to Happiness".
Puerto Rico Highway 8 (PR-8) is a main highway that serves as a third route from San Juan, Puerto Rico to Carolina, Puerto Rico. It is, still, a highly congested highway, noticeable when congestion jams are found in PR-17 where PR-8 begins and it continues to PR-3. The first kilometers of PR-8 were known before as Puerto Rico Highway 4, but the Department of Transportation renumbered the entire highway PR-8 and there is no longer a PR-4. It ends in PR-3 in Carolina.
Puerto Rico Highway 901 (PR-901) is a highway in the southeast coast of Puerto Rico which begins at its junction with PR-182 in Yabucoa and ends at its intersection with PR-760 in Manuabo.
Puerto Rico Highway 301 (PR-301) is a main highway in Cabo Rojo, Puerto Rico. It begins in PR-101, close to PR-100, and goes south all the way to Los Morrillos Light, where it ends. It is the main access to the lighthouse, the Cabo Rojo cliffs, and Playa Sucia.
Puerto Rico Highway 344 (PR-344) is a rural road in Hormigueros, Puerto Rico, beginning from near the municipality's small downtown and ending at PR-348 near the border with San Germán in barrio Rosario. It has narrow lanes, and after about five kilometers becomes one of the most dangerous highways in Puerto Rico, as it goes near a precipice with little or no safety barriers. It serves as a route to Mayagüez via PR-348 which ends in Puerto Rico Alt Route 2.
The Ruta Panorámica, officially the Ruta Panorámica Luis Muñoz Marín, is a 167-mile (269 km) network of some 40 secondary roads which traverse the island of Puerto Rico from west to east along its Cordillera Central. Most of the route consists of three roads, PR-105, PR-143, and PR-182. The route starts in Mayagüez and ends in Maunabo. The first major segment of the route runs from Mayagüez to Maricao as Route 105, then from Adjuntas to Aibonito as Route 143, and then follows Route 182 toward Maunabo.
Avenida Juan Ponce de León, coextensive as Route PR-25 along its entire length, is one of the main thoroughfares in San Juan, Puerto Rico.
Puerto Rico Highway 29 (PR-29) is an avenue in the city of Bayamón, Puerto Rico. It connects from the PR-2 to the PR-5, intersects the PR-167 at Plaza del Sol. This road is called Avenida Main Oeste.
Puerto Rico Highway 159 (PR-159) is the main road from Morovis to Toa Alta, passing through the municipality of Corozal, Puerto Rico.
Puerto Rico Highway 42 (PR-42) is an urban road in Santurce. This is a short road that connects from the PR-39 to Lafayette Street and intersects with PR-2. It is parallel to the PR-35 and PR-25. This road is called Calle Las Palmas.
Puerto Rico Highway 16 (PR-16) is an urban road in Santurce, Puerto Rico.
Puerto Rico Highway 34 (PR-34) is an urban road located in Caguas, Puerto Rico. This road extends from Avenida José Garrido (PR-196) in Cañabón barrio to PR-183 in Tomás de Castro barrio, and is part of Turabo and Degetau avenues.
Puerto Rico Highway 32 (PR-32) is an urban road in Caguas, Puerto Rico. This road goes from PR-1 in Bairoa to PR-172 in Turabo, east of downtown, and it is known as Avenida Luis Muñoz Marín.
Puerto Rico Highway 693 (PR-693) is a road located between the municipalities of Dorado, Puerto Rico and Vega Alta, passing through downtown Dorado. It begins at its intersection with PR-2 and PR-165 in Río Lajas and ends at PR-690 in Sabana. It is a short divided highway in southern Dorado, which serves as an alternate route for PR-165 west of Río de la Plata.
Puerto Rico Highway 760 (PR-760) is a rural road located in Maunabo, Puerto Rico. It begins at its intersection with PR-3 near downtown Maunabo and ends at Punta Tuna Light.
Puerto Rico Highway 200 (PR-200) is a road located in Vieques, Puerto Rico. This highway extends from Mosquito to Puerto Diablo, passing through Isabel II.
Puerto Rico Highway 633 (PR-633) is an east–west rural road located between the municipalities of Ciales and Morovis, Puerto Rico. It begins at its intersection with PR-149 in Hato Viejo barrio and ends at its junction with PR-155 in Barahona.
PR-760 in Emajagua–Quebrada Arenas–Maunabo barrio-pueblo 
PR-3 in Quebrada Arenas–Maunabo barrio-pueblo–Talante 
