Leitrim, a county in the north-east of the province of Connaught, in Ireland. Its greatest length, north-east to south-west, 51 miles; greatest width, 21 miles. Area, 376,212 acres, or 588 sq. m., of which 282,400 are arable, 11 per cent. barren, and 7 per cent. bog. The county touches the ocean on the north, and is divided into two parts by Lough Allen (q.v.), from which the Shannon forms the south-west boundary of the county. The southern division contains numerous small lakes. The northern division is intersected by several ridges. To the north of Lough Allen the soil, except at rare intervals, is unfavourable for agriculture, and the climate damp and ungenial. Leitrim is more a grazing than a tillage district, 53 per cent. of its area being grass-land. Potatoes and oats are the only crops of consequence. Coal is found in the Lough Allen basin; and iron and lead ores are abundant, although mining operations are very sparingly carried on. Linens and coarse woollens are manufactured for domestic use. The county town is Carrick-on-Shannon. Leitrim returns two members. Pop.
(1841) 155,297; (1861) 104,744; (1881) 90,372; (1891) 78,618. Leitrim was reduced by the English in the reign of Elizabeth, but revolted in 1588, submitting once more in 1603. The confiscations which followed the Civil War practically extinguished the native proprietary and the family of O'Rourke to whom it had once belonged.