Before the year 1954, Alinam was a sitio of Barangay San Isidro Cauayan City, Isabela. During that time there were only four (4) in the said sitio. As years passed by, a group of people from the province of Pangasinan came and occupied the place, hence, and population gradually increased.
In 1954, Alinam became a Barrio when Hilario Casanding Sr. was appointed tiniente del Barrio by the late Mayor Africiano. When tiniente del Barrio Hilario Casanding Sr. left his Barrio, he was succeeded by Pedro Vergara was succeeded by Daniel Peralta. In 1977, a Bliss Housing Project was constructed for the low-income families. There were fifty (50) units of Bliss Housing was erected.
In 1983, Orlando Castro, the number one councilman at that time, was appointed Barangay Captain until such time when he was defeated by Mr. Marcelo Viernes Jr. in the polls held in 1989. In the recent election (Barangay) held last May 1994, Mr. Alfredo Pulido emerged as the newly elected Barangay Captain. Barangay Captain Pulido is the 6th Brgy. Captain of Alinam, and finished his term last October 29, 2007. Mr. Domingo M. Pulido Sr. won the 2008 Election and finished his three executive terms. Mr. Ronald V. Peralta emerged as the newly elected Barangay Captain. Captain Ronald V. Paralta is the 8th Brgy. Captain of Alinam.