Cagayan, which included the sub-province of Batanes, was initially divided into two representative districts in 1907.
However, residents of two towns that had been annexed from Mountain Province — Allacapan (1928) and Langangan (1922) — were not extended the right to vote in assembly or senatorial elections until 1935, after the passage of Act No.
84 issued by Philippine Executive Commission Chairman Jorge Vargas on August 31, 1942, the province of Batanes was abolished and its territory was placed under Cagayan's jurisdiction for the duration of the Second World War.
Two delegates represented the province in the National Assembly of the Japanese-sponsored Second Philippine Republic: one was the provincial governor (an ex officio member), while the other was elected through a provincial assembly of KALIBAPI members during the Japanese occupation of the Philippines.
Cagayan was reapportioned into three congressional districts under the new Constitution[2] which was proclaimed on February 11, 1987, and elected members to the restored House of Representatives starting that same year.