Carolina (Spanish pronunciation: [kaɾoˈlina]) is a municipality located on the northeast coast of Puerto Rico. It lies immediately east of the capital San Juan and Trujillo Alto; north of Gurabo and Juncos; and west of Canóvanas and Loíza. Carolina is spread over 12 barrios plus Carolina Pueblo (the downtown area and administrative center). It is part of the San Juan-Caguas-Guaynabo Metropolitan Statistical Area, and home to Puerto Rico's main airport, the Luis Muñoz Marín International Airport.
The town was founded by Spanish colonists in 1816 as Trujillo Bajo ("lower Trujillo"), along with its counterpart Trujillo Alto after Trujillo, Spain. In 1857 it was renamed to San Fernando de la Carolina, later shortened to Carolina, after Charles II of Spain.
The city is known as "Tierra de Gigantes" (Land of Giants), not only for well-known Carolina resident Don Felipe Birriel González (who was 7'11"), but also in honor of other people from Carolina, including poet Julia de Burgos and most notably the first Latin American player named to baseball's Hall of Fame, Roberto Clemente. Carolina was also home to Jesús T. Piñero, the first Puerto Rican to be appointed as governor by the United States government. The city is also known as "El Pueblo de los Tumba Brazos" (The Arm Hackers Town). During the late 1800s, the town's major export was sugar cane. Sugar cane workers solved their issues by fighting with their machetes, and therefore many lost their arms.
In 1899, Carolina had a total population of 11,965.
Carolina municipality has a number of rivers such as the Río Canovanillas, Río Grande de Loíza, La Torrecilla, Piñones Lagoons.
Like all municipalities of Puerto Rico, Carolina is subdivided into barrios.