History Yvelines was created from the western part of the former department of Seine-et-Oise on 1 January 1968 in accordance with a law passed on 10 January 1964 and a décret d'application (a decree specifying how a law should be enforced) from 26 February 1965. It inherited Seine-et-Oise's official number of 78 since it took up the largest portion of its territory. In addition to this, it inherited Seine-et-Oise's prefecture, Versailles.
History Yvelines was created from the western part of the former department ,of Seine-et-Oise on 1 January 1968 in accordance with a law passed on 10 January 1964 and a décret d'application (a decree specifying how a law should be enforced) from 26 February 1965. It inherited Seine-et-Oise's official number of 78 since it took up the largest portion of its territory. In addition to this, it inherited Seine-et-Oise's prefecture Versailles.