Alstahaug is a municipality in Nordland county, Norway. It is part of the Helgeland region. The administrative centre of the municipality is the town of Sandnessjøen. Some of the villages in Alstahaug include Søvika and Tjøtta. Most residents of Alstahaug live in the town of Sandnessjøen which is situated on the island of Alsta. The characteristic Seven Sisters mountain range is found on the eastern part of the island. Local legend has made this chain of peaks into seven sisters, two adjacent peaks representing twin sisters. The island is connected to the mainland via the large Helgeland Bridge along Norwegian County Road 17. The Sandnessjøen Airport, Stokka is located 10 km south of Sandnessjøen. The municipality is the 307th largest by area out of the 356 municipalities in Norway. Alstahaug is the 136th most populous municipality in Norway with a population of 7,333. The municipality's population density is and its population has decreased by 0.5% over the previous 10-year period. The large municipality of Alstahaug was established on 1 January 1838 (see formannskapsdistrikt law). In 1862, the southern district (population: 2,781) was separated to become the new municipality of Tjøtta (Vevelstad Municipality was later separated from Tjøtta). This left Alstahaug with about 3,280 residents. Just two years later, in 1864, the western island district (population: 2,438) was separated to become the new municipality of Herøy. Then on 1 July 1899, the northern district (population: 2,673) was separated to form the new municipality of Stamnes (Leirfjord Municipality was later separated from Stamnes). During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1965, several major municipal changes took place. First, the Husvær island area of Alstahaug (population: 461) was transferred from Alstahaug to Herøy Municipality.