Which highway in the Philippines is the longest, running from Laoag to Zamboanga?

The Philippines’ longest highway, running from Laoag to Zamboanga, is the Pan-Philippine Highway.

Also called the Maharlika Highway, it forms the country’s north–south transport backbone. The route links Luzon, Samar, Leyte and Mindanao through roads, bridges and ferry connections, and is designated Asian Highway 26. Its listed road length is about 3,379.73 kilometres, excluding sea routes.

The highway was developed in the 1960s and was substantially rehabilitated in 1997 with Japanese assistance. It is also associated with National Route 1, although the Pan-Philippine route includes ferry crossings between islands. That detail explains why its road mileage and end-to-end travel distance can be reported differently.

“Maharlika Highway” is the common alternative name; Mindanao Highway and Luzon Highway refer to regional or informal descriptions, not the canonical Laoag–Zamboanga route.