Long time ago, Calaocan was formerly a sitio of Barrio Sta. Maria. Early settlers came from different places and community became the melting pot of San Nicolas in that period. Some came from western towns of the province like San Jacinto, San Fabian and Binmaley. Some originated from the Ilocos Provinces while others from the mountain of Itogon, Benguet. Calaocan became the meeting place of the east and west of the province. Different dialects were spoken and different customs and traditions were likewise practiced by the different groups of settlers but interacting together cooperatively and live peacefully as a community. Because of this, the community was called “laoclaoc” meaning mixed together. Later, it became “Calaocan” or a place where mixture of people resided. Acknowledged pioneers of Calaocan were Alejandro Mejia II, Don Carlos Ramos, Don Teofilo Soriano, Rufino Rosario, Maximo Vicente and Luzano Ibasco.

          It first came to existence as a barangay in the early 60’s by virtue of the PACD, creation of barangay, to foster countryside development Calalocan is bounded on the west by Brgy. Cabitnongan, on the east by Brgy. Sta. Maria East, on the south by Brgy. Nining and on the north by the Ambayoan River.

          Endowed with rich and fertile soil, hardworking people and good irrigation system, Calaocan indulges a year round cultivation and production of rice, corn and vegetables like sitaw, eggplant, ampalaya and okra. Other sources of income are livestock raising and overseas employment. The main canal of the National Irrigation Administration, the Ambayoan Irrigation System passes through the eastern most portion of the barangay providing ample water supply and roads were asphalt-paved, traverses the barangay making transportation of goods and people towards the town proper so convenient. Calaocan is a devout religious community with Protestants (of the United Methodist) as the dominant religious sect. Others belong to the Roman Catholics, Pentecostal, Christ is Coming and Born Again Christians. The barangay is  composed of three sitios namely; Sitio Siblot, Sitio Carayan and Sitio Centro.

           Some municipal leaders came from this barangay and to mention a few are former councilors  Don Carlos Romero, Don Manuel Rosario and Don Teofilo Soriano. Prominent families in the community are the Mejia, Ramos, Estrada, Vicente, Ibasco, Ligpit, Abad and Ventura.

            At present, the barangay is headed by Brgy. Capt. Rolando S.  Mejia and council members Reynaldo de Jesus, Toedy B. Santiago, Leonida M. Ramos,  Orlando M. Ramos, Leopoldo E. Serdana, Felipe C. Bautista , and Pedro Soriano, SK Chairman Conrado Abad, Jr., with Marina V. Torio and Lucita P. Pascua as Secretary and Treasurer, respectively. These  present  set of officials are working tremendously in the upliftment of the life of their constituents. So far, they were able to assist in the expansion of the water supply lines of the SANIWAD to Brgy. Calaocan, expanded the electric  lines of PANELCO III to interior sitios, construct five deep wells for potable water consumption, build their barangay hall, install street lights  along the provincial highway, widened and repaired their  barangay roads.

            And no matter where they came from, or what dialect they speak, and what culture and religion they practiced, the people of Calaocan are working hand in hand towards a more progressive Calaocan in the next generation.

Summary:

Barangay:    Calaocan

Population:    874 (1995 census)

No. of Households:    190 (Census)

Land Area:    263 has.

Diatnce from Municipal Hall:    2.5 kms.

Facilities:    Barangay Hall/Day Care Center/Basketball Court (Cemented)

 Road Condition:   Asphalted/Cemented

Public Utility Vehicle:   Tricycle/Kuliglig

Source of Potable Water:   Deep Well/SANIWAD

Mineral Resources:

Source of Electric Power:   PANELCO

School:   Elementary

Tourist Attraction: 

Farm Product:   Palay/Corn/Beans