BACUNGAN, the original name of the Municipality, was created in 1982, more specifically on March 25, 1982, by virtue of Batas Pambansa Bilang 204, authored by then Assemblyman Guardson Lood in the later part of the Marcos Era.
It composed of and curbed out from the Municipality of Sindangan, from out of the several barangays south of its jurisdiction, with barangay Bacungan as the core and set up of the newly created Local Government Unit (LGU).
After the passage of Batas Pambansa Bilang 204, the political machinery was set up; part of it was the placement, through appointment, of the first seat of local officials of the newly created Municipality.
Likewise, the required Municipal site was set up in preparation to the construction of its Municipal Hall, Municipal Plaza.
The LGU attainment of its Municipal site was acquired through a donation. Out of the nationalistic and patriotic nature of the heirs of the late Leon Bayot Postigo, an Ex-Philippine Constabulary corporal who owned a big tract of land in the heart of Bacungan, said heirs donated a 10-hectares lot as the Municipal site which is now part of the entire Municipal site consisting 13.3 hectares and where most of the local government buildings stand including the Public Market, Municipal Gym, Health Center and the Municipal Hall.
Part of the terms and conditions that went along with the contract/ agreement of donation was a condition to re-name Bacungan to Leon B. Postigo, in honor and memory of the late Leon B. Postigo.
Complying with the changing of the name condition, in the year 1989, after the lapse of 7 years, finally Bacungan was officially changed to LEON B. POSTIGO, through a legislative process: Republic Act No. 6830 was passed and approved by Congress legalizing the change.