In 1948, San Policarpo was created from the barrios of San Policarpo, Bahay, Alugan, Pangpang, Japonan, Tabo, Binogawan and Cajag-wayan, which used to belong to this town. The territory of the town was further reduced two years later, when Arteche was created from the barrios of San Ramon, Carapdapan, Beri, Tangbo, Catumsan, Bego, Concepcion, Casidman, Tawagan, and Tibalawon.
In 1952, the sitios of Trinidad, Tula, Pota, Palao, Sinalo-an, Tamse-on, Cagmalobago, and Maycorot, in the barrio of Agsam, were separated from said barrio and created into the barrio of Trinidad. In the same year, Sta. Monica was transferred to the town of San Policarpo.