Aguirre was in Spain's
gazetteers 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 Aguirre barrio was 1,291. Aguirre was once a municipality, until it was merged into Salinas during the 1990s. Before that, Aguirre was Puerto Rico's smallest municipality, a distinction now held by
Cataño near
San Juan. The
Central Aguirre Historic District was listed on the U.S.
National Register of Historic Places in 2002. For many years, Aguirre's main economical support came from the Central Azucarera de Aguirre, a local sugar factory. Aguirre still has a "central" but this one is operated by the
Autoridad de Energía Eléctrica de Puerto Rico, a government energy company. On Monday, July 25, 2016, there was a fire at the plant when there was an unnoticed petroleum leak. No one was injured, but the central's plants were unworkable for the following three weeks. The Central Azucarera de Aguirre was placed on the 2020 World Monuments Watch by the World Monuments Fund organization. The organization will use the site as a focal educational resource to train people in Puerto Rico on building with wood. {{US Census population| align= center ==Transportation==