CARLOW, a county of Ireland in the province of Leinster, bounded north by the counties Kildare and Wicklow, east by Wicklow and Wexford, south by Wexford, and west by Laorghis Co. (formerly Queen's Co.) and Kilkenny. Excepting Louth, it is the smallest county in Ireland, having an area of 221,539 acres. Pop. (1926), In the south-east is a range of barren granitic mountains, the chief peaks being Knockroe (1,746 ft.) and Mt. Leinster (2,610 f t.) . This range is flanked on the east by mica-schists and Silurian slates and on the west by Carboniferous limestone, the level ex panse of which covers the greater portion of the county. On the west side, the Barrow affords means of communication with Waterford whilst to the east the drainage is chiefly to the Slaney. Beyond the Barrow is 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. Glacial deposits cover much of the lower land and many eskers may be seen near Bagenalstown.
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 com prise large dolmens, some relics of ecclesiastical and monastic buildings, and 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. The soil is rich but stock-raising has become the most important rural activity. Sheep, poultry and dairy cattle are kept and the farms are often large. The staple trade of the county is in corn, flour, meal, butter and provisions, which are exported in large quan tities. 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 neigh bourhood of Tullow, but no attempt is made to turn this product to use.
The Great Southern 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. Co. Carlow and Co. Kilkenny together form one constituency returning five members to the Dail Eireann.