Santo Domingo, officially the Municipality of Santo Domingo (; ), is a municipality in the province of Ilocos Sur, Philippines. According to the , it has a population of people.
The name of the municipality came from its old moniker, "Paggappuan ti Santol iti Domingo," an Ilocano term meaning "The source of the Santol sold every Sunday." Santol (Sandoricum koetjape) is the name of the tree bearing round, yellowish fruits growing in abundance in the municipality, notably in Barangay Pussuac.
During the Spanish era, an enlisted man of the Spanish Civil Guard, Pablo Arquero, looked for the source of the santol being sold in the markets of Ciudad Fernandina (now Vigan City) on Sundays during the months of June to August. To do so, he asked for a leave of absence from his platoon leader to trace the source of the fruits. With his Ilocano guide, he searched the lands north of Villa Fernandina. He found nothing in the neighboring towns of Bantay, Santa Catalina, San Vicente, and Bantaoay (now San Ildefonso). He finally found many santol-bearing trees in a place north of Bantaoay now called Barangay Pussuac. He has found the "Paggappuan ti Santol ti Domingo." The town was named Santo Domingo on account of this feat.
Don Pablo Arquero is claimed to have founded the municipality on May 12, 1742, with Father Tomas Millan as the first parish priest. Father Millan laid the foundation of the belfry, where the great Filipino hero Diego Silang once worked as a boy. The 1818 Spanish census showed Santo Domingo had 2,942 native families co-progressing with 86 Spanish-Filipino families.
In 2010, the University of Northern Philippines opened a campus in Quimmarayan. It houses the university's agricultural, fishery and research courses; and the Environmental Research and Training Center.
Santo Domingo is situated from the provincial capital Vigan, and from the country's capital city of Manila.
Santo Domingo is politically subdivided into 36 barangays. Each barangay consists of puroks and some have sitios.
In the 2024 census, Santo Domingo had a population of 29,372 people. The population density was .
Santo Domingo, belonging to the first congressional district of the province of Ilocos Sur, is governed by a mayor designated as its local chief executive and by a municipal council as its legislative body in accordance with the Local Government Code. The mayor, vice mayor, and the councilors are elected directly by the people through an election which is being held every three years.
For 378 years, from 1521 to 1899, Local Chief Executives of the âÂÂpueblosâ or town were appointed by the Spaniards and in the year 1901 up to 1946 they were appointed by Americans. Afterwards, election was the mode of selection.
Gobernadorcillos (1742-1892):
Capitan Municipal (1893-1899):
Presidentes Municipal:
Municipal Mayors:
The Sto. Domingo-San Ildefonso Schools District Office governs all educational institutions within the municipality. They also oversee the operations of all private and public elementary and high schools located in San Ildefonso, Ilocos Sur.