The system of local government Ireland, then wholly within the United Kingdom of Great Britain and Ireland, was reformed by the Local Government (Ireland) Act 1898, which came into force in 1899. The new system divided Ireland into the following entities:

At the county level:

• Administrative counties; and
• County boroughs

Within the administrative counties:

• Municipal boroughs, governed by the Municipal Corporations (Ireland) Act 1840;
• Urban districts; and
• Rural districts

Some counties contained rural districts only, with no municipal boroughs or urban districts.

A number of small towns located in rural districts also had town commissioners with limited powers under the Towns Improvement (Ireland) Act 1854.

• List of rural and urban districts in Northern Ireland (1921—1972)

• "Alphabetical index to the county districts of Ireland". Census of Ireland, 1901: General topographical index. Command papers. Vol. Cd.2071. Dublin: HMSO. 1904. pp. 1040–1042.
• "Supplement to the alphabetical index to the county districts". Supplement to the general topographical index of Ireland. Command papers. Vol. Cd.6756. Dublin: HMSO. 1913. p. 17.
• Local Government Board for Ireland 27th Annual Report , 1900: (Containing Various Orders Made Modifying Boundaries Under the Local Government Act 1898 ). Command papers. Vol. C.9480. Dublin: HMSO. 1900. pp. 1–1022.
• Department of Industry and Commerce (1928). "Table 9. Population, Area and Valuation of Urban and Rural Districts and of all Towns with a Population of 1,500 Inhabitants or over, Showing Particulars of Town and Village Population and of the Number of Persons per 100 Acres" (PDF). Census of Population 1926. Vol. 1–Population, Area and Valuation of each DED and each larger Unit of Area. Dublin: Stationery Office. pp. 19–29. Retrieved 6 June 2018.