List of Irish local government areas 1899–1921

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.