Bohuslän (Swedish pronunciation: [ˈbuːhʉːsˌlɛːn]) (Norwegian: Båhuslen) is a Swedish province in Götaland, on the northernmost part of the country's west coast. It is bordered by Dalsland to the northeast, Västergötland to the southeast, the Skagerrak arm of the North Sea to the west, and the county of Østfold, in Norway, to the north.

Bohuslän is named after the Norwegian medieval castle of Båhus. Under the name Båhuslen, it was a Norwegian county from the unification in the 870s until the Treaty of Roskilde in 1658, when the kingdom of Denmark-Norway lost this area as well as Skåneland to Sweden.

The provinces of Sweden serve no administrative function. Instead, that function is served by the counties of Sweden. For centuries, the administrative county for Bohuslän was the Gothenburg and Bohus County, and as its name implies it consisted of the entire Bohuslän province together with the city Gothenburg. In 1998, some Swedish counties were merged to reduce administration costs, and Gothenburg and Bohus County were therefore merged into the new, much larger Västra Götaland County.

Bohuslän was granted its arms at the time of the funeral for Charles X Gustav of Sweden in 1660. It was identical to the arms of the Town of Kungälv. In 1962 the higher claim of the town was established and a variation for the arms of the county was introduced. The coat of arms is surmounted by a ducal coronet. Blazon: "Argent, a Castle embattled Gules with one embattled Tower of the same and two doors Or hinged Sable between a Sword point upwards and Lion rampant holding the Tower both Azure langued and armed Or."

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