The province and the city were represented in the lower house of the Congress of the Philippines through their lone congressional district.
Maguindanao del Norte (including Cotabato City) first gained separate representation in 1984, when it returned two representatives, elected at large, to the Regular Batasang Pambansa.
Under the new Constitution which was proclaimed on February 11, 1987, Maguindanao del Norte, including Cotabato City, was retained into one congressional district;[2] each elected its member to the restored House of Representatives starting that same year.
The province of Shariff Kabunsuan, established with the passage of Muslim Mindanao Autonomy Act No.
[3] It was this specific provision that became the subject of the Supreme Court case that ultimately voided MMA Act No.