The highway system in Puerto Rico is composed of approximately 14,400 kilometers (8,900 mi)  of roads and is maintained by Puerto Rico's Department of Transportation and Public Works (Spanish: Departmento de Transportación y Obras Públicas) or DTOP. The highway system in Puerto Rico is divided into four networks: primary, urban primary, secondary or inter-municipal, and tertiary or local (Spanish: primaria, primaria urbana, secundaria o intermunicipal, y terciaria o local).  Highways may change between networks and retain their same numbers. In addition, there is a fifth network of local roads called Municipal Roads and they are maintained by the local Municipalities. These roads are not numbered and they do not have kilometer markers.
Puerto Rico roads are classified according to the network they belong to. Thus there are four types: 
|Highway type||Highway Shield|
|Urban Primary Roads|
|Secondary (or inter-municipal) Roads|
|Tertiary (or intra-municipal) Roads|
In this regard, a primary road is one which is part of the Primary Network, an urban primary road is part of the Urban Primary Network, etc. Generally, the same highway may change between networks, but the highway will continue to have the same number. For example, PR-1, connecting Ponce and San Juan, is signed as Urban Primary inside the Ponce city limits, then it is signed as Secondary in Ponce's rural barrio Capitanejo, and then it is again signed as Urban Primary on its entry into the town of Santa Isabel.
Primary roads are numbered 1 through 99, secondary roads are numbered 100 to 299, and tertiary roads are numbered 300 to 9999. 
Until 1999,[ citation needed] all non-tolled numbered highways in Puerto Rico had the same route shield, a square with a white-on-black half-circle with the route number in the bottom two thirds and a map of Puerto Rico with the words "Puerto Rico" written inside in the top third.
This article or section appears to contradict itself.(February 2015)
All Puerto Rico Highway System roads, regardless of the network they belong to are maintained by the centralized, Commonwealth-level, Departmento de Transportacion y Obras Publicas (DTOP). Municipal governments are not responsible for maintenance of the Puerto Rico Highway System roads within their territory whether or not the municipal government is an autonomous government or not; DTOP is the responsible agency.  The DTOP maintains a network of regional offices throughout the island which carry out DTOP work within their multi-municipality region. Municipal governments are only responsible for maintenance of the non-numbered (Municipal Roads), as well as the city and town streets within their jurisdictions.  On occasion, the central government has entered into MOAs with municipal governments for the collaborative maintenance of some Puerto Rico Highway System roadways within their municipalities.  
Puerto Rico has 410 km (250 mi) of Interstate highways.  There are three designated Interstate Highways in Puerto Rico.  As with Interstate Highways in Alaska and Interstate Highways in Hawaii, these routes do not connect to the rest of the United States Interstate Highway System, but still receive funding in a similar fashion to the Interstates in the contiguous US.
As with Interstate routes in Alaska, Puerto Rico Interstate routes are unsigned. The designated routes of the three routes — officially PRI-1, PRI-2 and PRI-3  — run along various combinations of Puerto Rico routes. They do not follow the rules of even and odd numbers determining direction used in mainland United States. Per Section 103(c)(1)(B) (ii), Title 23, United States Code (23 U.S.C.) Puerto Rico is exempt from the design standards of Section 109(b). 
|71.08||114.39||PR-2 in Ponce||PR-2 in San Juan (PR 22/PR 18 interchange)|
|138.13||222.30||PR-1 in Ponce||PR-3 in San Juan (PR 1/PR 26 interchange)|
|65.27||105.04||PR-3 in Humacao||PR-2 in San Juan (PR 1/PR 26/PR 66 interchange)|
Expressways in Puerto Rico are controlled-access highways, or limited-access roads. Many are tollways whose funding are collected by a system of tolls  rather than the United States Interstate Highway System, however, some parts of Puerto Rico's unsigned interstate highways are concurrent with the tolled expressways. Most tollbooths accept AutoExpreso, an electronic toll collection system, to avoid traffic congestion. 
All Puerto Rico expressways are signed either as primary or as primary urban routes.
|Route||Name||Terminus||Maximum speed limit||Comments|
|PR-2||Expreso Kennedy||Starts from San Patricio Plaza (Guaynabo) to Santurce (San Juan, aka Parada 18).||50 mph (80 km/h)||Guaynabo to San Juan section only.|
|PR-2||Roberto Sanchez Vilella||Starts from Mayagüez Mall (Mayagüez) to PR-1 in Ponce||55 mph (90 km/h)||Mostly converted to expressway from Mayagüez Mall to Ponce.|
|PR-5||Expreso Río Hondo||Bayamón, PR-22 to Naranjito, PR-147 and PR-149 with discontinuity between PR-199 in Bayamón and PR-167 in Toa Alta.||50 mph (80 km/h)||Tolled. This road has three expressway segments as of April 2012—these are between PR-29 and PR-22 and between PR-2 and PR-199 (both in Bayamón), an unbuilt portion in southern Bayamón and a portion between PR-167 ( Toa Alta) and the town of Naranjito.|
|PR-9||Baldorioty de Castro||PR-10 Barrio Portugues to PR-2 Barrio El Tuque||55 miles per hour (89 km/h) to 65 miles per hour (105 km/h)||From PR-123 to PR-2 still under construction|
|PR-12||Santiago de los Caballeros||PR-14 Barrio Machuelo Abajo to PR-123 Barrio Playa||55 miles per hour (89 km/h)|
|PR-18||Expreso Las Américas||PR-22 San Juan and PR-52 San Juan||55 to 65 mph (90 to 110 km/h)|
|PR-20||Expreso R. Martínez Nadal||PR-2 in the San Patricio area in Guaynabo to PR-1 in La Muda sector in Caguas||55 mph (90 km/h)||Tolled|
|PR-22||Autopista José de Diego||Hatillo, PR-2 to San Juan, PR-26||65 mph (105 km/h)||Extension to Aguadilla in planning. Tolled|
|PR-26||Expreso Román Baldorioty de Castro||San Antonio Bridge (Bridge to Old San Juan Island) to PR-3 in Carolina.||65 mph (105 km/h)|
|PR-30||Expreso Cruz Ortiz Stella||Caguas, PR-1 to Humacao, PR-53||55 mph (90 km/h)|
|PR-52||Autopista Luis A. Ferré||Ponce, PR-2 to San Juan, PR-1 and PR-18||65 mph (105 km/h)||Tolled. This highway is the longest tolled freeway in Puerto Rico.|
|PR-53||Autopista Dr. José Celso Barbosa||Fajardo to Yabucoa, and then Guayama to Salinas.||65 mph (105 km/h)||Maunabo tunnels constructed in October 2008. The segments between Yabucoa and Maunabo still incomplete.|
|PR-60||Avenida Dionisio Casillas||Humacao, PR-30 to Humacao, PR-3||55 mph (90 km/h)|
|PR-66||Autopista Roberto Sánchez Vilella||PR-3 in Carolina and Rio Grande||65 mph (105 km/h)||Second half opened in October 2012 to Rio Grande. Tolled.|
|PR-165||Expreso El Caño||Guaynabo, PR-2 and PR-23 to Cataño||50 mph (80 km/h)|
Below is a list of some highways in Puerto Rico along with the municipalities where they begin and end.
Primary roads are numbered in the 1 to 99 range and are distributed randomly throughout the island.
|Number||Length (mi)||Length (km)||Southern or western terminus||Northern or eastern terminus||Formed||Removed||Notes|
|PR-1||79.85||128.51||PR-123 in Ponce||Calle Tanca in San Juan||—||—|
|PR-2||143||230||PR-1 / PR-133 in Ponce||PR-26 in San Juan||1953||current|
|PR-2R||0.54||0.87||PR-440 in Aguadilla||PR-2 in Aguadilla||—||—|
|PR-2R||3.3||5.3||PR-2 / PR-114 in Mayagüez||PR-2 in Mayagüez||—||—|
|PR-2R||1.01||1.63||PR-2 in Ponce||PR-123 in Ponce||—||—|
|PR-3||102||164||PR-1 in Salinas||PR-1 in San Juan||—||—|
|PR-3R||—||—||PR-3 in San Juan||PR-8 in San Juan||—||—||Unsigned|
|PR-3R||0.9||1.4||PR-3 in Humacao||PR-3 in Humacao||—||—|
|PR-4||2.9||4.7||—||—||—||—||Renumbered as PR-8|
|PR-5||15.66||25.20||PR-164 in Naranjito||Calle Canal in Cataño||—||—||PR-5 exists into two segments due to an unconstructed portion in Bayamón.|
|PR-6||1.86||2.99||PR-5 in Bayamón||PR-2 in Bayamón||—||—|
|PR-8||2.9||4.7||PR-17 in San Juan||Near PR-3 in Carolina||—||—||Formerly PR-4|
|PR-9||4.52||7.27||PR-2 / PR-52 in Ponce||PR-10 in Ponce||2006||current||PR-9 currently exists in two portions, as the portion between PR-123 and PR-500 is actually under construction.|
|PR-10||42.41||68.25||PR-5506 in Ponce||PR-2 in Arecibo||—||—||PR-10 exists into two segments due to an unconstructed portion between Adjuntas and Utuado.|
|PR-12||3.28||5.28||La Guancha in Ponce||PR-14 in Ponce||—||—|
|PR-14||44.29||71.28||PR-123 in Ponce||PR-1 in Cayey||—||—|
|PR-14R||0.56||0.90||PR-123 in Ponce||PR-14 in Ponce||—||—|
|PR-15||15.67||25.22||PR-3 in Guayama||PR-14 in Cayey||—||—|
|PR-16||0.52||0.84||PR-1 in San Juan||PR-1 / PR-26 in San Juan||—||—|
|PR-17||7.1||11.4||PR-19 in San Juan||PR-26 in Carolina||—||—|
|PR-18||3.78||6.08||PR-1 / PR-52 in San Juan||PR-22 in San Juan||—||—|
|PR-19||1.5||2.4||PR-20 in San Juan||PR-2 in Guaynabo||—||—||PR-19 is the main avenue in San Patricio, Guaynabo.|
|PR-20||6.02||9.69||PR-1 in Guaynabo||PR-2 in Guaynabo||—||—|
|PR-21||2.98||4.80||PR-20 in San Juan||PR-1 / PR-176 in San Juan||—||—|
|PR-22||52||84||PR-2 in Hatillo||PR-26 in San Juan||—||—|
|PR-23||3.84||6.18||PR-2 / PR-165 in Guaynabo||PR-27 in San Juan||—||—|
|PR-24||1.1||1.8||PR-165 in Guaynabo||PR-888 in Cataño||—||—|
|PR-25||7.14||11.49||PR-3 in San Juan||Calle Recinto Sur in San Juan||—||—|
|PR-25R||2||3||PR-1 in San Juan||PR-25 in San Juan||—||—|
|PR-26||9.63||15.50||PR-1 in San Juan||PR-3 / PR-66 in Carolina||1982||current|
|PR-27||3.04||4.89||PR-3 in San Juan||PR-36 in San Juan||—||—|
|PR-28||3.8||6.1||PR-5 in Bayamón||PR-2 in Guaynabo||—||—|
|PR-29||2.2||3.5||PR-2 in Bayamón||PR-5 in Bayamón||—||—|
|PR-30||19.07||30.69||PR-1 in Caguas||PR-53 in Humacao||—||—|
|PR-31||15.91||25.60||PR-30 / PR-9913 in Juncos||PR-3 in Naguabo||—||—|
|PR-32||4.5||7.2||PR-172 in Caguas||PR-1 in Caguas||—||—|
|PR-33||1.2||1.9||Bulevar Cristóbal Colón in Caguas||PR-1 / PR-189 in Caguas||—||—|
|PR-34||2.6||4.2||PR-32 in Caguas||PR-196 in Caguas||—||—|
|PR-35||2.6||4.2||PR-1 in San Juan||PR-16 in San Juan||—||—|
|PR-36||1.1||1.8||PR-35 in San Juan||PR-27 in San Juan||—||—|
|PR-37||4.1||6.6||PR-25 in San Juan||PR-187 in Carolina||—||—|
|PR-38||0.67||1.08||Calle Recinto Sur in San Juan||PR-25 in San Juan||—||—|
|PR-39||0.6||1.0||PR-1 in San Juan||PR-25 in San Juan||—||—|
|PR-40||0.6||1.0||PR-25 in San Juan||PR-27 in San Juan||—||—|
|PR-41||1.6||2.6||PR-17 in San Juan||PR-25 in San Juan||—||—|
|PR-42||0.7||1.1||Calle Lafayette in San Juan||PR-39 in San Juan||—||—|
|PR-47||1.7||2.7||Calle Ferrocarril in San Juan||PR-3 in San Juan||—||—|
|PR-52||67.29||108.29||PR-2 / PR-9 in Ponce||PR-1 / PR-18 in San Juan||1969||current|
|PR-53||59||95||PR-52 in Salinas||PR-3 / PR-194 in Fajardo||1994||current||PR-53 exists into four portions due to an unconstructed segments between Guayama and Yabucoa.|
|PR-54||3.5||5.6||PR-53 / PR-7711 in Guayama||PR-3 / PR-748 in Guayama||—||—|
|PR-60||2.2||3.5||PR-30 in Humacao||PR-3 in Humacao||—||—|
|PR-63||0.37||0.60||PR-102 in Mayagüez||PR-2 in Mayagüez||—||—|
|PR-64||3.5||5.6||PR-102 / PR-3342 in Mayagüez||PR-2 / PR-342 in Mayagüez||—||—|
|PR-65||0.57||0.92||PR-2R in Mayagüez||PR-106 in Mayagüez||—||—|
|PR-66||12.4||20.0||PR-3 / PR-26 in Carolina||PR-3 / PR-187 in Río Grande||2006||current|
|PR-70||—||—||PR-8 in San Juan||PR-874 in Carolina||—||—||Unsigned|
|PR-71||—||—||PR-8 in San Juan||Near PR-26 in Carolina||—||—||Unsigned|
|PR-71R||—||—||PR-70 in Carolina||PR-71 in Carolina||—||—||Unsigned|
|PR-72||—||—||PR-8 / PR-3R in San Juan||PR-70 in Carolina||—||—||Unsigned|
|PR-73||—||—||PR-72 in Carolina||PR-70 in Carolina||—||—||Unsigned|
Secondary roads are numbered in the 100 to 299 range. Unlike primary highways, which are numbered randomly throughout the island, secondary highways generally follow a grid pattern. They begin from the southwest portion of the island with PR-100 and increase in number as you progress in a northeasternly fashion. PR-100 is located in the southwestern town of Cabo Rojo, whilst PR-198 is in Juncos, Las Piedras and Humacao in the eastern part of Puerto Rico. The highest secondary highway number assigned so far (February 2014) is 252 (PR-252), located in the northeastern municipality-island of Culebra. A few roads "violate" this grid order; for example, PR-199 lies in Guaynabo and San Juan.
Tertiary highways also follow a general grid. Towns which do not border the Atlantic Ocean or the Caribbean Sea, especially in the mountainous area, may overlap this grid, for example Ciales may have both highways in the 600-699 grid and the 500-599 grid, depending where they begin further north or further south. Generally along the areas where the highways are, the lower the number, the more south it is. Culebra is the only town in Puerto Rico that does not fall in any of the regions, for only PR-250 and PR-251 are the main routes. The entire immediate metropolitan area of San Juan with the exception of Caguas falls in the 800 region, while the entire east coast (north and south) east of San Juan, Caguas and Patillas fall in the 900 region. This is because the eastern portion of Puerto Rico has a southeastern coast which goes to the west from Humacao, which roughly defines where the Vieques Passage and the Caribbean Sea meet along the coast. Yabucoa is in the exact south-southeast area and lies in the 900 region, while Maunabo overlaps the 700's and 900's regions. Vieques, an offshore island-municipality, has some highways in the 900 order.
Some roads are numbered using four digits. For example, PR-5506. These are branches, or spurs, of tertiary roads by the same last three digit number. Thus, PR-5506 is a branch of PR-506. They are often dead end branches, and are common in the mountain regions of the main island. Sometimes they are loops branching off the main road and eventually connecting back to the same main tertiary road. The "fourth" digit is generally a repeat of the first digit of the main tertiary road in question. Thus, a branch of PR-301 would be signed PR-3301, with the added "3" prefixing the number of the main tertiary road associated with the spur, 301, because "3" is the first digit of the main road. When the road has more than one distinct spur, an additional unrelated digit is used (example, PR-4301).
- Autoridad de Carreteras y Transportacion (December 22, 2004). "Guias para la Seleccion e Instalaccion de Rotulos de Orientacion (Suplemento al MUTCD 2003)" (PDF) (in Spanish). Departamento de Transportación y Obras Públicas. p. 2. Archived from the original (PDF) on November 4, 2009. Retrieved January 3, 2015.
- Autoridad de Carreteras y Transportación (December 22, 2004). "Guias para la Seleccion e Instalaccion de Rotulos de Orientacion (Suplemento al MUTCD 2003)" (PDF) (in Spanish). Departamento de Transportación y Obras Públicas. p. 1. Archived from the original (PDF) on November 4, 2009. Retrieved January 5, 2015.
- Autoridad de Carreteras y Transportación Estándares de Ingeniería. "Chapter i: General Design Criteria". Manual de Diseño (PDF) (in Spanish). Departamento de Transportación y Obras Públicas. Sections 1-03.01, pp. 1-2. Archived from the original (PDF) on November 22, 2009. Retrieved January 5, 2015.
- "Municipal Ordinance Number 52, Series 2009-2010. Primera Hora" (PDF) (in Spanish). Autonomous Municipality of Ponce. April 28, 2010. p. 59.
- "Oficinas Regionales" (in Spanish). Departamento de Transportación y Obras Públicas. Archived from the original on September 6, 2010. Retrieved August 22, 2010.
- "ACT Propone Diseño de Mejoras Geometricas Para Agilizar el Transito en las Rampas de Acceso de la PR-52 Hacia y Desde Juana Diaz" (Press release) (in Spanish). Departamento de Transportación y Obras Públicas. November 16, 2010.
- "Municipio de Ponce Repavimenta la PR-2". El Sur a la Vista. Ponce, Puerto Rico (in Spanish). September 16, 2011. Retrieved September 19, 2011.
- "Section D: Puerto Rico Highways" (PDF). Latin America Trade and Transportation Study. Mississippi Department of Transportation. March 2001.
- DeSimone, Tony (April 6, 2011). "Table 3: Interstate Routes in Each of the 50 States, District of Columbia, and Puerto Rico". Route Log and Finder List. Federal Highway Administration. Retrieved July 4, 2012.
- DeSimone, Tony. "Additional Designations". Route Log and Finder List. Federal Highway Administration. Retrieved March 14, 2010.
- "Table 1: Main Routes of the Dwight D. Eisenhower National System Of Interstate and Defense Highways as of October 31, 2002". Route Log and Finder List. Federal Highway Administration. June 4, 2012. Retrieved July 4, 2012.
- "Tarifas de Estaciones de Peaje" (in Spanish). Department of Transportation and Public Works of Puerto Rico. Retrieved December 28, 2012.
- "AutoExpreso" (in Spanish). Department of Transportation and Public Works of Puerto Rico. Archived from the original on December 23, 2012. Retrieved December 28, 2012.