Sørfold is a municipality in Nordland county, Norway. It is part of the traditional district of Salten. The administrative centre of the municipality is the village of Straumen. Other villages in the municipality include Leirfjordgården, Mørsvikbotn, Røsvika, Rørstad, Styrkesvik, and Øvre Kvarv. The municipality surrounds the Sørfolda fjord and stretches east to the border with Sweden. The municipality is the 48th largest by area out of the 356 municipalities in Norway. Sørfold is the 286th most populous municipality in Norway with a population of 1,869. The municipality's population density is and its population has decreased by 6.7% over the previous 10-year period. The municipality of Sørfolden was established on 1 January 1887 when the old municipality of Folden was divided into two: Sørfolden (population: 1,946) and Nordfold-Kjerringøy (population: 1,347). The spelling was later changed to just Sørfold. On 1 January 1894, the Movik farm (population: 30) along the Sagfjorden was transferred from Nordfold-Kjerringøy municipality to Sørfold municipality. During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1964, the Øyjord area along the Nevelsfjorden (population: 81) was transferred to the neighboring municipality of Bodin. On the same date, the Mørsvikbotn area (population: 268) was transferred from Nordfold Municipality to Sørfold Municipality. On 1 January 1984, the Tårnvika and Øygården area (population: 22) along the Sørfolda fjord was transferred from Sørfold to Bodø Municipality. The municipality is named after the local Folda fjord (Fold). The first element is the prefix Sør- which means "Southern". The last element is fold which has an unknown meaning (maybe "the broad one"). The inner part of the fjord is divided into two arms Nordfolda ("the northern Folda") and Sørfolda ("the southern Folda"). The coat of arms was granted on 24 April 1987. The official blazon is "Azure, a turbine wheel argent" (I blått et sølv turbinhjul).