 Davao del Sur was represented in the Interim Batasang Pambansa as part of Region XI from 1978 to 1984, and returned two representatives, elected at-large, to the Regular Batasang Pambansa in 1984.Davao City separately elected its own representatives starting that year.Under the new Constitution which was proclaimed on February 11, 1987, Davao del Sur was reapportioned into two congressional districts; each elected its member to the restored House of Representatives starting that same year.