Legislative districts of Ilocos Sur

The Legislative districts of Ilocos Sur are the representations of the province of Ilocos Sur in the of the Philippines. The province is currently represented in the lower house of the Congress of the Philippines through its first and second districts.

Abra last formed part of the province's representation in 1919.

The first district of Ilocos Sur is among the original representative districts from 1907 which has never changed in territorial coverage, along with Albay's first, Ilocos Norte's first and second, and Iloilo's first, districts.

Ilocos Sur, which at the time included the sub-province of Abra, was initially divided in 1907 into three representative districts. Abra was last represented as part of the province's now-defunct third district in 1919, after its re-establishment as a regular province on 10 March 1917 by virtue of Act No. 2683 warranted its separate representation, thereby reducing Ilocos Sur to two districts.

When the Philippine Commission detached Tagudin from Ilocos Sur and made it the capital of the sub-province of Amburayan in Mountain Province on 15 May 1907 by virtue of Act No. 1646, the town's residents were still allowed to vote as part of the Ilocos Sur's second district. This arrangement was terminated on 10 August 1916 under Act No. 2657 (the Administrative Code of the Philippine Islands), which removed the town from the second district.

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