The cultural shock brought by the dominating social and economic regulations introduced by the Spanish authorities propelled the natives to dissent in the Mallig and the Ilagan-Tumauini territories in what was known as the Gaddang Revolution.

The fortunes of Isabela as a province and Ilagan as a town followed a similar path to the rest of the country's history as a commonwealth nation and as a free republic in 1942, the Japanese occupation, liberation, political and military independence to this day.

[23] When Ferdinand Marcos' September 1972 declaration of Martial law began 14 years of authoritarian rule, the province of Isabela, including the municipality of Ilagan became a center of both conflict and protest when Marcos cronies Danding Cojuangco and Antonio Carag managed to block a Spanish-era grant which was supposed to see the return of Hacienda San Antonio and Hacienda Santa Isabel in Ilagan to local farmers.

In the Social Action Center's newsletter, the "Courier," researcher Sabino Padilla Jr. documented and exposed the ways by which Cojuangco, Carag, the provincial government, and the military harassed the farmers who were supposed to get the land.

By virtue of Republic Act 10169,[37] Ilagan was then proclaimed as a new component city, the third in the province of Isabela and the fourth in Cagayan Valley on the same day by COMELEC Commissioner Armando Velasco.

Among the services included is the Department of Social Welfare and Development’s (DSWD) Assistance to Individuals in Crisis Situations (AICS) program, which provided a provincial wide payout in the three cities and 34 municipalities of the province of Isabela.

Other regulatory functions of the Philippine National Police (PNP), Department of Foreign Affairs (DFA), Land Transportation Office (LTO), National Bureau of Investigation (NBI), Philippine Statistics Authority (PSA), Professional Regulation Commission (PRC), Social Security System (SSS), PhilHealth, Government Service Insurance System (GSIS), and the Bureau of Internal Revenue (BIR) also extended their programs and services during the two-day caravan.

Ilocanos who already developed their own distinct traits were recorded to have migrated massively in the 19th century owing to the accessibility of the land and vast opportunities in the area straddling the present-day provinces of Cagayan and Nueva Vizcaya.

[109][110] The groundbreaking ceremony of the City of Ilagan Feed Mill Complex and the signing of the Memorandum of Agreement between Charoen Pokphand Foods, Sagittarian Agricultural Phils., Inc. and Kasetphand Group was held on May 17, 2024.

[111][112] This kind of joint venture between the government and private sector is essential for the delivery of basic services and business matching opportunities specifically for corn farmers who will be the primary recipient of the project.

[172][173][174] Ilagan Sanctuary[175][176] is a 200-hectare protected area located within the 819-hectare Fuyot Springs National Park along the foothills of the Sierra Madre mountain range in Barangay Santa Victoria, fifteen kilometers away from the city proper.

[185][186][187] On January 9, 2024, the city government of Ilagan ordered the temporary closure of Abuan River and its surrounding areas to all picnics and recreational activities to give way for its planned rehabilitation and development.

Additional facilities/amenities for water adventure rides like kayaks, boats, jet-ski, All-Terrain Vehicles (ATVs), paragliding, LED/solar lights, steel cottages and comfort rooms were added to lure more local tourists and visitors from neighboring towns and provinces.

[202] It displays artifacts that preserve and give insight into Isabela's natural and cultural history such as fossils, ethnographic items, heirloom pieces, photographs, paintings, sculptures, other visual arts, dioramas, and miniature models of provincial landmarks, among others.

Beside the park is a popular attraction called Banchetto Ilagan, which is usually frequented by locals and visitors especially when the city government transforms the area into a Christmas themed village during the holiday season.

[228][229][230][231][232] The final investigation report of the Bureau of Fire Protection (BFP) identified the total cost of the damages is estimated to be around P35-40 million which include antique religious items among others.

The Department of Public Works and Highways (DPWH) and Ilagan City Engineering Office conducted a series of tests and studies which revealed that only around 20-30% of the structural integrity of the church remained after the fire took down most of its interior.

[268] Celebrated during the last week of May; Mammangi is an Ibanag term that signifies the esteemed Ilagueño corn farmers, recognized as the backbone of the city’s thriving economy which encompasses the entire agricultural cycle, from land preparation - plowing, tilling, planting to nurturing, harvesting, drying, and delivering produce from farm to market.

[340][341][342] The City of Ilagan Community Center is a fully air-conditioned facility that was built to accommodate indoor events such as basketball games, badminton and volleyball tournaments, cheerdance competitions, concerts, and other important activities.

[351][352] The sports complex was erected by the National Government and local officials during the presidency of Fidel V. Ramos as a permanent facility for the province of Isabela, in barangay Alibagu, Ilagan, the capital.

[375][376] After months of feasibility study and coordination of all parties involved, the proposed multi-billion project was officially unveiled to the public on November 24, 2023 during its groundbreaking ceremony at the Ilagan City Integrated Central Terminal in barangay Alibagu, the first of its kind in the Northern Philippines.

The 100.0 MW Solar PV project will help alleviate the current electricity shortage in the country that causes regular blackouts resulting in industry closures as well as inconvenience to the consumers.

[433] The consortium pledged to invest in future projects which include the construction of Sewage Water Treatment Facilities in Barangays Namnama and Santa Catalina in 2024 to attain the Sustainable Plan & Development towards the goal of becoming a liveable city by 2030.

Also, the authorities added that the Pasa Dam project would further fortify Isabela as the country's leading agriculture province, which has kept the title as a top corn producer and second in rice production.

[435][436][437][438] On February 21, 2021, the City Government of Ilagan spearheaded the ground-breaking ceremony for the Phase 1 of the P250 million worth Multi-Purpose Sports, Commercial and Convention Center with a total maximum capacity of up to 10,000 seats, the biggest of its kind in Northern Luzon.

The subdivision-type housing project is situated beside Richmond Hills Subdivision, few meters away from Xentro Mall (Northstar) and the City of Ilagan Civic Center in barangay Alibagu.

[462] On November 22, 2023, the Philippine Statistics Authority - Civil Registry System (PSA-CRS) Outlet was officially opened and inaugurated to cater the Central Cagayan Valley Region.

[511][512] Ilagan is the center of education in the province of Isabela especially for neighboring municipalities of Tumauini, Gamu, Burgos, Roxas, Quirino, Naguilian, Benito Soliven, San Mariano and Delfin Albano.

[526] The city government allotted P100 million for the construction of the said higher educational institution that is expected to offer health allied courses which include Nursing, Medical Laboratory Science, Pharmacy, Dentistry, Optometry and more.

The newly inaugurated facility is expected to serve as PNP’s Recruitment and Training Center that will cater to police trainees all over Luzon including the National Capital Region.