Region I: Ilocos Region

The Ilocos Region (Ilocano: Rehion/Deppaar ti Ilocos; Pangasinan: Sagor na Baybay na Luzon) is an administrative region of the Philippines, designated as Region I, occupying the northwestern section of Luzon. It is bordered by the Cordillera Administrative Region to the east, the Cagayan Valley to the northeast and southeast, and the Central Luzon to the south. To the west lies the South China Sea.

Region 1 was first inhabited by the aboriginal Negritoes before they were pushed by successive waves of Malay/Austronesian immigrants that penetrated the narrow coast. Tingguians in the interior, Ilocanos in the north, and Pangasinense in the south settled the region. Before the administration of Ferdinand Marcos, Pangasinan was not a part of the region.

The Ilocos Region occupies the narrow plain between the Cordillera Central mountain range and the South China Sea, and the northern portion of the Central Luzon plain, to the north-east of the Zambales Mountains. Lingayen Gulf is the most notable body of water in the region and it contains several islands, including the Hundred Islands National Park. To the north of the region is Luzon Strait. The Agno river runs through Pangasinan flowing into a broad delta at the vicinity of Lingayen and Dagupan before emptying into the Lingayen Gulf.