The province of Ilocos Sur is the second northernmost province of Region I (Ilocos Region). It is located along the western coast of Northern Luzon bounded by the South China Sea on the west, the province of Ilocos Norte on the north, the province of Abra on the northeast, Mountain Province on the east and the province of La Union on the south. Vigan City, the provincial capital, lies approximately four hundred and eight (408) kilometers north of Manila, one hundred thirty nine (139) kilometers north of San Fernando City, La Union, the Regional Capital and eighty (80) kilometers south of Laoag City, Ilocos Norte. Sixteen (16) municipalities and the two (2) cities, Vigan and Candon are located along the coast and generally at the lowland areas. The other sixteen (16) municipalities are at the interior areas, fourteen (14) of which are cradled along the Cordillera Mountains at the eastern portion of the province and generally characterized as mountainous areas because of the rugged terrain and swift major rivers and waterways traversing these areas. 


The province spans an area of approximately two thousand five hundred ninety six (2,579.58) square kilometers (sq. kms.) the second smallest province in the region, occupying about 20.09% of the total land area of Ilocos Region. It is about 0.86% of the Philippines Land Area of three hundred thousand (300,000) square kilometers ( sq. km). 

Land Area by Province, Region I

Province Land Area (sq. km.) % Distribution 
Ilocos Norte 3,504.30 26.47 
Ilocos Sur 2,579.58 20.09 
La Union 1,497.70 11.63 
Pangasinan 5,368.18 41.81 
Total – Region I 12,949.76 100% 
Total Philippines 300,000.00 0.86% 

Source: RPFP 2004-2030

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The province is divided into two (2) political districts, the first and second district. It has two (2) component cities, Vigan City which is the Provincial Capital East at the first district and Candon City at the second district. There are thirty two (32) municipalities of the Province, ten of which are at the first district with two hundred ninety six (296) barangays including the barangays of Vigan City. It represents 39.54% of the total barangays. The other twenty two (22) municipalities are at the second district with four hundred seventy two (472) barangays including the barangays of Candon City representing 61.46% of the total seven hundred sixty eight (768) barangays Province wide. Vigan City, being the Provincial capital hosts the Provincial Capitol and serves as center of education, business and trade and other economic and social activities. Only two (2) municipalities of the first district that do not have coasts and is generally low land. Most of the Municipalities of the second district are at upland areas especially at the eastern portion. Candon city and eight (8) other municipalities at the second district are coastal LGUs. Most economic activities and services are centered at the low land areas hence most of the populations are at these areas. The municipality of Sta. Cruz has the most number of barangays (49) followed by Sinait (44) and Tagudin (43). Candon City has forty two (42) barangays while Vigan City has thirty nine (39). Sugpon with only six (6) barangays with Sigay and San Vicente having 7 barangays each are the LGUs with the least number of barangays.

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Table 2. Land Area and Number of Barangays by City/Municipality by District, Ilocos Sur
City/ MunicipalityArea (in Sq. Km.)Number of Brgys.
First District
1. Vigan 27.4039
2. Bantay 76.6034
2. Cabugao 60.1033
3. Caoayan 26.0017
4. Magsingal 85.2030
5. San Ildefonso 17.2015
6. San Juan 52.1032
7. San Vicente 15.1007
8. Sta. Catalina 13.5009
10. Sto. Domingo 57.8036
11. Sinait 80.7044
Sub-Total 511.70296
Second District
12. Candon City 76.942
13. Alilem 156.209
14. Banayoyo 31.214
15. Burgos 44.326
16. Cervantes 230.713
17. Galimuyod 34.424
18. G. del Pilar 104.207
19. Lidlidda 29.711
20. Nagbukel 34.912
21. Narvacan 98.434
22. Quirino 240.109
23. Salcedo 23.121
24. San Emilio 132.808
25. San Esteban 23.410
26. Santa 51.626
27. Santa. Cruz 101.649
28. Santa Lucia 49.936
29. Santa Maria 49.633
30. Santiago 74.524
31. Sigay 114.607
32. Sugpon 182.806
33. Suyo 124.008
34. Tagudin 58.343
Sub-Total 2067.2472
ILOCOS SUR 2,579.58768

Land Area Distribution by District, Ilocos Sur

1st District – 19.80%

2nd District80.20%

The first district shares only 1/5 of the total land area of the province. The smallest town is Sta. Catalina with only 13.5 sq. kms. which is only 0.52% of the provincial total. This is followed by San Vicente, San Ildefonso and Caoayan, Ilocos Sur. The municipality of Quirino is the biggest municipality of the province in terms of land area, followed by Cervantes, Sugpon, Alilem and Suyo. The aggregate area of these 5 municipalities totaled to 933.8 sq. kms. These 5 municipalities occupy the southeastern portion of the province along the Cordillera Mountain. The land area of Candon City is almost three times bigger than Vigan City, the provincial capital.