CARLOW, a county of Ireland in the province of Leinster, bounded N. by the counties Kildare and Wicklow, E. by Wicklow and Wexford, S. by Wexford, and W. by Queen’s county and Kilkenny. Excepting Louth, it is the smallest county in Ireland, having an area of 221,424 acres, or about 346 sq. m. The surface of the county is in general level or gently undulating, and of pleasing appearance, except the elevated tract of land known as the ridge of Old Leighlin (Gallows Hill Bog, 974 ft.), forming the beginning of the coal-measures of Leinster, and the south-eastern portion of the county bordering on Wexford, where the wild and barren granitic elevations of Knockroe (1746 ft.) and Mount Leinster (2610 ft.) present a bolder aspect. Glacial deposits, which overspread the lower grounds, sometimes afford good examples of the ridge-forms known as eskers, as in the neighbourhood of Bagenalstown. There are no lakes nor canals in the county, nor does it contain the source of any important river; but on its western side it is intersected from north to south by the Barrow, which is navigable throughout the county and affords means of communication with the port of Waterford; while on the eastern border the Slaney, which is not navigable in any part of its course through the county, passes out of Carlow into Wexford at Newtownbarry.
Carlow is largely a granite county; but here the Leinster Chain does not form a uniform moorland. The mica-schists and Silurian slates of its eastern flank are seen in the diversified and hilly country on the pass over the shoulder of Mt. Leinster, between Newtownbarry and Borris. The highland drops westward to the valley of the Barrow, Carlow and Bagenalstown lying on Carboniferous Limestone, which here abuts upon the granite. On the west of the hollow, the high edge of the Castle-comer coalfields rises, scarps of limestone, grit, and coal-measures succeeding one another on the ascent. Formerly clay-ironstone was raised from the Upper Carboniferous strata.
The soil is of great natural richness, and the country is among the most generally fertile in the island. Agriculture is the chief occupation of the inhabitants, but is not so fully developed as the capabilities of the land would suggest; in effect, the extent of land under tillage shows a distinctly retrograde movement, being rather more than half that under pasture. The pasture land is of excellent quality, and generally occupied as dairy farms, the butter made in this county maintaining a high reputation in the Dublin market. The farms are frequently large, and care is given to the breeding of cattle. Sheep and poultry, however, receive the greatest attention. The staple trade of the county is in corn, flour, meal, butter and provisions, which are exported in large quantities. There are no manufactures. The sandstone of the county is frequently of such a nature as to split easily into layers, known in commerce as Carlow flags.
Porcelain clay exists in the neighbourhood of Tullow; but no attempt is made to turn this product to use.
The Great Southern & Western railway from Kildare to Wexford follows the river Barrow through the county, with a branch from Bagenalstown to Kilkenny, while another branch from the north terminates at Tullow.
As regards population (41,964 in 1891; 37,748 in 1901), the county shows a decrease among the more serious of Irish counties, and correspondingly heavy emigration returns. Of the total, about 89% are Roman Catholics, and nearly the whole are rural. Carlow (pop. 6513), Bagenalstown (1882), and Tullow (1725) are the only towns. The county is divided into seven baronies, and contains forty-four civil parishes and parts of parishes. It belongs to the Protestant diocese of Dublin and the Roman Catholic diocese of Kildare and Leighlin. The assizes are held at Carlow, and quarter sessions at that town and also at Bagenalstown and Tullow. One member is returned to parliament.
Carlow, under the name of Catherlogh, is among the counties generally considered to have been created in the reign of John. Leinster was confirmed as a liberty to William Marshal, earl of Pembroke, by John, and Carlow, among other counties in this area, had the privileges of a palatinate on descending to one of the earl’s heiresses. The relics of antiquity in the county comprise large cromlechs at Browne’s Hill near Carlow and at Hacketstown, and a rath near Leighlin Bridge, in which were found several urns of baked earth, containing only small quantities of dust. Some relics of ecclesiastical and monastic buildings exist, and also the remains of several castles built after the English settlement. Old Leighlin, where the 12th century cathedral of St Lazerian is situated, is merely a village, although until the Union it returned two members to the Irish parliament.