The President of the Philippines, Diosdado Macapagal in turn acted favorably to the proposal by issuing an executive order which provided that the new municipality was to exist upon the appointment of a mayor, a vice-mayor and councilors. The new municipality was to include the following barrios: Quirino, Ballogo, Ubbog, Paagan, Carcarmay, Nagatiran, Mabanengbeng II and Narra. The seat of the Government was to be in Quirino. However, no appointment of a municipality was created.
An attempt was made by the Provincial Board of La Union to create a municipality out of the town of Bacnotan.
By virtue of R.A. 2692 which was sponsored by then Congressman Francisco Ortega, the La Union Agricultural School was established. Nestling at the foot of the mountains of Barangay Sapilang, the agricultural school progressed and was later named Don Mariano Marcos Memorial State University. Its campus occupies an area of about 6 square kilometers.
CEPOC, a government-owned corporation, was sold to the privately owned Bacnotan Consolidated Industries (BCI). BCI is the manufacturer of "Union Cement".
The vast mineral deposits of limestone used in portland cement production were noticed in Barrio Dumarang (now Quirino) by a mining engineer who was then a municipal councilor at that time. Because of the desire to create economic activity, the municipal council, through the efforts of this mining engineer, invited potential investors to set up a Portland cement plant. Within a year, a cement plant called Cebu Portland Cement (CEPOC), was established.
Bacnotan became the provisional seat of provincial government, since San Fernando was then in ruins. As a consequence of this transfer, the La Union National High School was also moved to Bacnotan. When things went back to normal, the provincial government was again moved to San Fernando and the La Union National High School followed afterwards. The transfer of the provincial high school in Bacnotan resulted in the establishment of the North Provincial High School (now Bacnotan National High School.).
The tides of war changed in La Union as Filipino and American soldiers captured the strategic Baroro Bridge in Bacnotan, which connects the rest of Northern Luzon to San Fernando. It was followed by the historic Battle of San Fernando and Bacsil Bridge. The victory ensured the liberation of La Union Province by joint Filipino and American troops at the end of World War II.
During the first days of World War II, invading Japanese forces reached Bacnotan.
When La Union was created, Bacnotan was one of the 12 towns that formed the province.