Cagayan Valley , designated as Region II, is an administrative region in the Philippines. Located in the northeastern section of Luzon, it is composed of five Philippine provinces: Batanes, Cagayan, Isabela, Nueva Vizcaya, and Quirino. The region hosts four chartered cities: Cauayan, Ilagan, Santiago, and Tuguegarao (the regional center and largest city).
Most of its land area lies in the valley between the Cordilleras and the Sierra Madre mountain ranges. The eponymous Cagayan River, the country's largest and longest, runs through the region, flows from the Caraballo Mountains, and ends in Aparri. Cagayan Valley is the second-largest Philippine administrative region by land area. According to a literacy survey in 2019, 93% of Cagayan Valley's citizens (ages 10 to 64) are functionally literate, which is 5th out of the 17 regions of the Philippines.