CAVAN, a county in the province of Ulster, Ireland, bounded north by Fermanagh and Monaghan, east by Monaghan and Meath, south by Meath, Westmeath and Longford, and west by Longford and Leitrim. Area 477,399 acres; pop. (1926), In the north-west is a mountainous district of millstone grit rising in Cuilcagh to a height of 2,188 ft. The source of the Shannon is thought to be near here. The central portion of the county is a low-lying area of carboniferous limestone, covered by numerous lakes, the most important of which is Lough Oughter, and drained chiefly by the river Erne. The land to the south-east is hilly and irregular and here are encountered the underlying Silurian strata that run from Longford to Donaghadee in Co. Down.
For some centuries after the English settlement this district was known as the Brenny, being divided between the families of O'Rourke and O'Reilly; and its inhabitants, protected by the nature of the country, long maintained their independence. In 1579 Cavan was made shire ground as part of Connaught, and in 1584 it was formed into a county of Ulster. The county subse quently came within the scheme for the plantation of Ulster under James I. Some few remains of antiquity exist in the shape of cairns, raths and the ruins of small castles, such as Cloughoughter castle on an island (an ancient crannog) of Lough Oughter. Three miles from the town of Cavan is Kilmore, with its cathedral, a plain erection containing a Romanesque doorway brought from the abbey of Trinity island, Lough Oughter. The bishopric dates from about 1450.
The climate suffers from dampness arising from the numer ous lakes. The soil is generally a stiff clay, cold and watery, but capable of much improvement by drainage, for which its un dulating surface affords facilities. Only about of the total area is quite barren. The farms are generally small; oats and potatoes are the principal crops. Flax, once of some importance, is almost neglected. In the higher lands are larger grazing farms which are fairly prosperous.
Cavan is not a manufacturing county. The bleaching of linen and the distillation of whisky are both carried on to a small extent, but the people are chiefly employed in agricultural pur suits and in the sale of home produce. The soil in those districts not well adapted for tillage is peculiarly favourable for trees. The woods were formerly very considerable, and the timber found in the bogs is of large dimensions; but plantations are now chiefly found in extensive demesnes.
The absence of large urban centres is reflected in the limited railway development. The Great Northern railway from Clones to Cavan and the Great Southern railway from Mullingar in West meath to Cavan form a through line from north to south. The Great Northern has branches to Belturbet from Ballyhaise, and to Cootehill from Ballybay ; the former is continued westwards by the Great Southern railway which has branches also to Killashandra, and from Navan in Meath to Kingscourt. Cavan returns four members to the Dail Eireann.