Ni County Codes in Alphabetical Order

In 1903, vehicle registration codes were assigned across the island of Ireland, organized alphabetically by counties and county boroughs. The codes ranged from IA to IZ and from AI to WI, excluding those containing G, Q, S, and V, as well as II. For example, Antrim was assigned IA, and Armagh received IB, while County Dublin, now part of the Republic of Ireland, was assigned IK, falling between IJ for Down and IL for Fermanagh.

Shortly before Ireland's partition in 1922, Belfast completed its OI series and was assigned the next available code, XI. Dublin City was then given YI and ZI. After the partition, codes starting with "Z" (e.g., ZA, ZB) were allocated to the Republic of Ireland, while those with "Z" as the second letter (e.g., AZ, BZ) were designated for Northern Ireland, except for County Mayo, which originally held IZ. In 2004, IG was assigned to Fermanagh, and in 2023, VI was allocated to the City of Derry/Londonderry.

County and City Codes