Sudipen is the northernmost town of the Province of La Union separated by the Amburayan River from the Province of Ilocos Sur.

According to a story which happened during the Spanish period, the town got its name when a group of Spanish soldiers reached barrio Nagpanaoan, now called Old Central. These soldiers came upon old folks who were repairing the roof of the barrio hall. One of the soldiers asked the name of the place. They did not understand what was the soldier was saying, but they still thought that the soldier wanted to know what was going on, so the eldest among the barrio folks answered: “suksukdipan mi toy abong apo,” meaning, “we are patching the roof, sir”. The soldiers noted the word “Sukdipan” and the word stayed on record for some time. Subsequently, under the American regime, the word sukdipan was changed to Sudipen, hence the name of the town.

Early settlers of the municipality belonged to the cultural minorities from Mountain Province. Remnants of these groups, mostly belonging to the Kankaney and Bago tribes, can still be found in mountain barangays. But through intermarriages between highlanders and lowlanders, the tribes spread throughout the municipality. For this reason, younger generations can no longer speak the cultural minority dialects.

There are two principal rivers in this town, one is the Amburayan River, which stretches along its northern and eastern border and the Lalonga or Chico River that dissects barangays Bigbiga, Bulalaan and Maliclico. Both rivers provide water resources both for agricultural and domestic purposes in the municipality and the neighboring towns of Bangar, Luna and Balaoan. Also, the Mini Hydro Power Plant located at Barangay Turod drew its water supply from these rivers.

It was noted that the Municipality got its name during the Spanish – American War in the Philippines. Originally, Sudipen was the Barrio of Bangar, La Union. In 1906, a village leader named Bartolome Laoagan Apusen succeeded in organizing it to township of the sub-province of Lepanto, Amburayan. Ten years after in 1916, the township became a municipal district of the Province of La Union. Finally on September 14, 1947, Sudipen was reclassified into a regular sixth class municipality.

Originally, the township was composed of 10 barangays or barrios namely: San Rafael, San Jose, San Francisco, Sengngat, Bigbiga, Castro, Duplas, Maliclico and Up-uplas. Barrio Nagpanawan was first sub-devided. It was late in 1950’s when Nagpanawan gave birth to Ilocano.

Barrio Ipet came later in late 1960 from barrio Ilocano. In 1962, barrio Turod evolved from barrio San Rafael. San Rafael consequently named barrio Poblacion being the seat of the Municipality. In 1967, Nagpanawan which was later named Old Central, sub-devided and barrio Namaltugan was born. Barrio San Francisco followed in 1971 deviding itself in San Francisco Sur and San Francisco Norte pursuant to Provincial Board Resolution No. 197 which took effect on March 12, 1971. Earlier, on the later part of 1970, Barrio Bulalaan was carved out of the barrio Duplas and prior to that Up-uplas sub-devided in September 21, 1968 resulting in the evolved of Porporiket.

At present, the Municipality of Sudipen comprises of 17 Barangays. Five are upland barangays while 12 are in lowlands.

Land Area : 10,048.714978 hectares (source: DENR RO 1)

Population : 17, 056 (source: 2015 Census of Population)

Number of Barangays : 17

Classification : Fourth Class Municipality

Average Annual Income : Php. 58,985,478.17

Total Households : 4,072

Total Families : 5,170