A municipality can be involved in a municipal redivision process, a municipal boundary adjustment or a shift from one province to another. The West Frisian Islands comprise Texel, Vlieland, Terschelling, Ameland and Schiermonnikoog. Texel and Ameland were never involved in a redivision process. Since 1 September 1942, Terschelling and Vlieland are part of the province of Friesland, instead of the province of North Holland. Schiermonnikoog was subject to a municipal and a provincial boundary adjustment on 1 January 2006.
Historical data on municipalities are extracted from Van der Meer and Boonstra, Repertorium van Nederlandse gemeenten 1812–2006. (The Hague, 2006)