Santiago, officially the City of Santiago, (Ilokano: Siudad ti Santiago; Ibanag: Siudad nat Santiago; Gaddang: Siudad na Santiago; Tagalog: Lungsod ng Santiago), or simply as Santiago City is a 1st class independent component city in Cagayan Valley (Region II), Philippines. According to the 2015 census, it has a population of 134,830 people. Formerly known as Pueblo de Carig in old Spanish time, it is located between southwestern part of Isabela and northwestern boundary of Quirino in Northeastern Luzon island of the Philippines.
It is the gateway to the vast plains of Cagayan Valley. Santiago is situated 331 kilometres (206 mi) north of Metro Manila. The city sits on a vast area of predominantly flat and fertile land in the Cagayan Valley, surrounded by the Caraballo Mountains to the south, the Great Sierra Madre to the east and the Cordillera Mountain Range to the west alongside of the great mighty magat river. Though statistically grouped by the Philippine Statistics Authority and geographically located within the boundaries of the province of Isabela, as well as part of the province's 4th District, Santiago City is administratively and legally independent from the province as stated in Section 25 of the LGC. The origin of Santiago City can be drawn from the first native settlement discovered by the early Spanish missionaries at the bank of the old Carig River (now Diadi River) from which its original name, Carig, was derived.