Vestfold [ˈvɛ̂stfɔɫ] is a traditional region, a former county and a current electoral district in Eastern Norway. In 2020 the county became part of the much larger county of Vestfold og Telemark. Located on the western shore of the Oslofjord, it bordered the previous Buskerud and Telemark counties. The county administration was located in Tønsberg, Norway's oldest city, and the largest city is Sandefjord. With the exception of the city-county of Oslo, Vestfold was the smallest county in Norway by area. Vestfold was the only county in which all municipalities had declared Bokmål to be their sole official written form of the Norwegian language.