The Municipality of Sudipen is located 312 km. northwest of Manila and about 43 north-northeast of San Fernando City, La Union. It is bounded on the west by towns of Bangar-Balaoan on the east and north by the famous Amburayan River and the Province of Ilocos Sur and on the south by the town of Santol, La Union.
Sudipen has a total land area of 10,048.714978 hectares. Among the barangays, Bulalaan has the largest land area with only 816.669 square meters and Barangay Turod has the smallest land area with 132.4607 sq. meters.
Agricultural land - 6,045.9473 hectares
Grassland / shrub land - 1,780.701 hectares
Wooden / forest - 298.3579 hectares
Bare land / Wetland - 431 hectares
Built-up - 609.586 hectares
Sudipen is generally mountainous. Of the total land area, forest, mountainous and hills cover about 63%. This topographic characteristic is
contributory to the poor facilities. Of the total land area 925 can be utilized for agriculture.
Major dialect in the municipality is composed of Ilocano 93.30 %, Kankanai 3.06 and Tagalog 0.5%.
Early settlers of the municipality belong to the cultural minorities from the Mountain Province. Remnants of these groups mostly belong to the Kankanai and Bago Tribes and they can still be found on upland barangays. But through inter-marriages of the uplanders and the lowlanders, the tribe spread throughout the municipality. However, most of the younger generation at this time are not speaking in the cultural minority dialects.