The six counties of Northern Ireland are the counties of Antrim, Fermanagh, Tyrone, Down, Armagh and Londonderry. These six counties are those that chose to become separate, independent entities after opting out of the Irish Free State in 1922.
The boundaries of the six counties of Northern Ireland have their roots in the centralized planning done during the early 16th century. The counties, however, existed in one form or another prior to this official division. The six counties were also local administrative centers of the region after the 1989 Local Government Act.
As of 2014, the six counties of Northern Ireland still have limited political status with car license plates being assigned identifiers according to their county of registration. Until 1996, the six counties were also used by the Royal Mail service for mail sorting.
In 1972, the six-county local administration system was replaced with a system of 26 unitary councils. These councils have boundaries which may cross existing county borders. As of 2014, these 26 unitary councils serve as the main form of local government in Northern Ireland and have limited authority over issues such as community services and building control.