Partition of Ireland
The partition of Ireland () divided the island of Ireland into two distinct jurisdictions, Northern Ireland and Southern Ireland. It took place on 3 May 1921 under the Government of Ireland Act 1920. Today the former is still known as Northern Ireland and forms part of the United Kingdom, while the latter is now a sovereign state also named Ireland and sometimes called the Republic of Ireland.
Administrative counties of Ireland
Administrative counties were a unit of local government created by an Act of the Parliament of the United Kingdom for use in Ireland in 1899. Following the separation of the Irish Free State from the United Kingdom of Great Britain and Ireland, administrative counties continued in use in the two parts of the island of Ireland under their respective sovereign jurisdictions. They continued in use until 1973 in Northern Ireland and until 2002 in the Republic of Ireland.