[1][2][3] 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 a territory of the United States.

In 1899, the United States Department of War conducted a census of Puerto Rico finding that the population of Naguabo was 10,873.

The highest point in the municipality is Pico del Este in the Sierra de Luquillo at 3,419 feet (1,042 m) of elevation.

The municipal buildings, central square and large Catholic church are located in a barrio referred to as "el pueblo".

Of the 742 places that were on the list in 2014, the following barrios, communities, sectors, or neighborhoods were in Naguabo: Relámpago neighborhood, Río, Santiago y Lima, Daguao, La Florida, Casco Urbano in barrio-pueblo, Húcares, Maizales, Parcelas La Fe, and Río Blanco.

The Fiestas Patronales de Nuestra Virgen del Rosario is a religious and cultural celebration that generally features parades, games, artisans, amusement rides, regional food, and live entertainment.

In 2024, Wanda Soto Tolentino and Luis Daniel Colón La Santa were elected as District Senators.