Sveitarfélagið Árborg is the biggest municipality in southern Iceland.
It was formed in 1998. The population of Árborg was 7,827 (January 2011). The biggest town in the municipality is Selfoss, with a population of 6,512. Eyrarbakki and Stokkseyri are two communities on the southern coast and Sandvíkurhreppur is a rural administrative region between those three other towns. It is also the 8th most pop. city in Iceland