San Fernando, La Union in the context of San Fernando, Pampanga

The Ilocos Region (Ilocano: Rehion/Deppaar ti Ilocos; Pangasinan: Rehiyon na Ilocos; Tagalog: Rehiyon ng Ilocos), designated as Region I, is an administrative region of the Philippines. Located in the northwestern section of Luzon, it is bordered by the Cordillera Administrative Region to the east, the Cagayan Valley to the northeast and southeast, Central Luzon to the south, and the South China Sea to the west. The region comprises four provinces: Ilocos Norte, Ilocos Sur, La Union, and Pangasinan, along with one independent-component city, Dagupan City. The regional center is the city of San Fernando in La Union, which serves as the administrative hub of the region. The largest settlement in terms of population is San Carlos City in Pangasinan.

The 2020 Philippine Statistics Authority census reported that the ethnolinguistic group composition of the region is predominantly made up of Ilocanos (58.3%), followed by Pangasinans (29.7%), Tagalogs (4.1%), and various Cordilleran (Igorot) indigenous groups.

La Union (Tagalog pronunciation: [lɐ ʔʊˈɲon]), officially the Province of La Union (Ilocano: Probinsia ti La Unión; Pangasinan: Luyag na La Unión; Kankanaey: Probinsya di La Unión; Ibaloi: Probinsya ni La Unión; Tagalog: Lalawigan ng La Unión; Spanish: Provincia de La Unión), is a coastal province in the Philippines situated in the Ilocos Region on the island of Luzon. The province's capital, the City of San Fernando, is the most populous city in La Union and serves as the regional center of the Ilocos Region.

Bordered by Ilocos Sur to its north, Benguet to its east, and Pangasinan to its south, with the South China Sea to the west, La Union is located 273 kilometers (170 miles) north of Metro Manila and 57 kilometers (35 miles) northwest of Baguio City. The province spans an area of 1,497.70 square kilometers (578.27 square miles). As of the 2020 census, La Union had a population of 822,352, resulting in a density of 550 inhabitants per square kilometer or 1,400 persons per square mile. The province had 538,730 registered voters as of 2022. The province official language is Iloco (Ilocano), as declared by the provincial government of La Union.