Legislative districts of Ilocos Sur

Ilocos Sur, which at the time included the sub-province of Abra, was initially divided in 1907 into three representative districts.

[1] When the Philippine Commission detached Tagudin from Ilocos Sur and made it the capital of the sub-province of Amburayan in Mountain Province on May 15, 1907, by virtue of Act No.

2877 in 1920 reorganized northwestern Luzon, by abolishing the sub-province of Amburayan in the undivided Mountain Province and annexing several of its municipal entities—Alilem, Sigay, Sugpon, Suyo and its capital Tagudin—to Ilocos Sur.

The Lepanto sub-province townships of Angaki, Concepcion, San Emilio and its capital Cervantes were also placed under the jurisdiction of Ilocos Sur.

The province retained its two congressional districts under the new Constitution[5] which was proclaimed on February 11, 1987, and elected members to the restored House of Representatives starting that same year.