All Puerto Rico Highway System roads, regardless of the classification used, are maintained by the centralized, Commonwealth-level, Departmento de Transportación y Obras Públicas (DTOP).

Municipal governments are only responsible for maintenance of city and town streets within their jurisdictions.

[7][8] In Puerto Rico, the term municipal road may be encountered occasionally.

Roadways that have both their terminus within the same municipality are called tertiary roads and are, by convention, numbered PR-300 through PR-9999.

However, if the term occurs in the context of roadways owned and maintained by a municipal government, it refers to the network of local streets and roadways that make up the urban landscape of a municipality.

[3] Most tollbooths accept the AutoExpreso, an electronic toll collection system, to avoid traffic congestion.

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.

They begin from the southwest portion of the island with PR-100 and increase in number as you progress in a northeasterly 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.

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.

They are often dead end branches, and are common in the mountain regions of the main island.

They do not follow the even-and-odd-number rule used in mainland United States that indicates direction of travel.