There are 32 traditional all-island counties in Ireland. This count refers to the historic counties covering the entire island, rather than only the present-day local-government areas of the Republic of Ireland.
Following the partition of Ireland in 1921, 26 of the traditional counties became part of the Irish Free State, now the Republic of Ireland, while six counties formed Northern Ireland. The 32-county framework remained important in geography, history, culture and sport even though political administration developed differently on either side of the border.
The counties are traditionally grouped into four provinces: Leinster has 12, Munster has six, Connacht has five and Ulster has nine. Six of Ulster’s nine counties are in Northern Ireland; the other three—Donegal, Cavan and Monaghan—are in the Republic.
A common source of confusion is the difference between traditional counties and modern administrative units. Dublin, for example, was reorganized into several local authorities, but County Dublin still counts as one of the historic 32.