[3][4][5] Piñales was in Spain's gazetteers[6] until Puerto Rico was ceded by Spain in the aftermath of the Spanish–American War under the terms of the Treaty of Paris of 1898 and became an unincorporated territory of the United States.

In 1899, the United States Department of War conducted a census of Puerto Rico finding that the population of Piñales barrio was 1,038.

[7] Piñales barrio became inaccessible when Hurricane Maria hit Puerto Rico on September 20, 2017 and caused landslides and destruction.

[8] Five months after the hurricane struck, engineers and officials were grappling with the massive amounts of repairs that were needed to PR-109 in Añasco and multiple other areas of this barrio and of Añasco, as a whole.

Barrios (which are, in contemporary times, roughly comparable to minor civil divisions)[15] in turn are further subdivided into smaller local populated place areas/units called sectores (sectors in English).