The Municipal Corporations (Ireland) Act 1840 followed the example of the legislation in England and Wales. Unlike the 1835 Act, the Irish Act abolished nearly all of the country's boroughs, reforming just 10. Inhabitants of the larger of the abolished boroughs or of any town with a population of 3,000 could petition the crown for incorporation under the Act. In the event, only one additional borough was created when Wexford received a charter of incorporation in 1846. The corporation and town council was identical in constitution to the English boroughs, and each borough was divided into wards with three, six or nine councillors per ward and one alderman for every three councillors.
The Local Government (Ireland) Act 1898 designated the six largest municipalities (Belfast, Cork, Dublin, Limerick, Londonderry and Waterford) as county boroughs. The Local Government (Ireland) Act 1919 introduced a system of proportional representation into municipal elections. Wards were replaced by electoral areas, and the entire council was to be elected triennially. Separate elections of aldermen and councillors were ended, with all members of the council elected by popular vote. One quarter of the elected members were entitled to the title of "alderman", which was used to designate the first candidates elected in each area. The remaining successful candidates being "councillors".
On partition in 1922, two boroughs were included in Northern Ireland, and nine in the Irish Free State.