 Prior to gaining separate representation, areas now under the jurisdiction of Zamboanga Sibugay were represented under the Department of Mindanao and Sulu (1917–1935), the historical Zamboanga Province (1935–1953), Region IX (1978–1984) and Zamboanga del Sur (1953–1972; 1984–2001).The passage of Republic Act No.8973 and its subsequent ratification by plebiscite on February 22, 2001 separated the entire third district of Zamboanga del Sur to form the new province of Zamboanga Sibugay.