Ilagan, officially the City of Ilagan (Ilocano: Ciudad ti Ilagan; Filipino: Lungsod ng Ilagan) (PSGC: 023114000), is a component city in the province of Isabela, Philippines. It is the provincial capital, the most populous city in the province, and with a total land area of 116,626 hectares (288,190 acres), the largest city in the island of Luzon and the fourth largest city (in terms of land area) in the Philippines, after Davao City, Puerto Princesa and Zamboanga City. Ilagan City has a population of 135,174 according to 2010 census.

In the recent elections, Ilagan City has a voting population of 90,250 as revealed by Commission on Elections but only 67% participated in the Midterm Election. Ilagan City still holds the title as the most number of voters in the province.

Ilagan City was a first class municipality before becoming a city.

History

The town was then called by its native Gaddang settlers as Bolo during the pre-Spanish conquest era. It is one of the populous settlement during that period and site of the vast tobacco plantation in the region making it one of the most important economic areas in northern Luzon. Shortly after Juan de Salcedo conquered Northern Luzon in 1587, Gov. Rodrigo de Penalosa sent Capt. Pablo de Carreon to explore Cagayan Valley as well as to establish missions in towns. Among the Spanish missionaries who penetrated deeply into the region was P. Pedro Jimenez, who founded Ilagan.