Etymology:
Unlike other municipalities, there are no legends to speak about the origin of the name Pilar. The municipality’s name however is derived from its Patron Saint Nuestra Señora Del Pilar. On the other hand, the municipality’s capital Poblacion or Baliwag is named after a merchant from Balioag, Bulacan, who settled early in the place engaging in commerce.
Creation of the Municipality
During the administration of Gobernador Don Joaquin de Paat y Parella in 1866, a pueblo which is named Villavieja was organized in the southwestern most portion of Abra due to the necessity of establishing a Catholic Mission. The new pueblo was formerly barangay Bolli-lising which was an interior territory. Villavieja then covered the territory now occupied by the Municipality of Pilar, San Isidro and Villaviciosa and the southern part of Luba. Due to the very extensive area covered by the town Villavieja,a new pueblo called pueblo de Lumaba was established in 1884 at Barangay Lumaba upon the order of Governor Jose Diaz Y. Sala.
In 1885, when Juan Valera succeeded Jose Prada Malaquim as Governadorcillo, the center of government was transferred to a terrain west of Lumaba just across the Sinalang River and was called Poblacion del Pilar in honor of its Patron Saint NuestraSeñora del Pilar.
In 1903, the pueblo of Villavieja and Pilar was merged to form a new town called Villa Pilar under the Government Act No. 1001 in accordance with the Policy of Philippine Commission towards consolidation. In the same year, due to cultural reason, the town of Villaviciosa was created and Villa Pilar was plainly called latter as PILAR.