The counties of Northern Ireland were the principal local government divisions of Northern Ireland from its creation in 1921 until 1972, when their governmental features were abolished and replaced with twenty-six unitary authorities. In total Northern Ireland consisted of six counties: Antrim, Armagh, Down, Fermanagh, Londonderry (also known as Derry) and Tyrone. These form two-thirds of the historical province of Ulster. The number has been used in the designation The Six Counties as an Irish-nationalist alternative name for Northern Ireland.