Mayo, a county on the west coast of Ireland, in the province of Connaught, having the Atlantic to the N. and W., Sligo to the N.E., Roscommon to the E., and Galway to the S.E. and S. The area is about 2,060 square miles, the eastern portion of which is tolerably level, whilst the western half consists of granitic mountains, with a few fertile valleys running down to the sea. The Moy is the only important river, but there are many lakes, including Loughs Mask, Corrib, and Carrowmore. Fish abounds, and but for this the wretched peasantry could hardly subsist on their small holdings of poor soil. Except a little coarse linen and rough homespun, there are no manufactures; the quarries of limestone and slate employ but few hands. Iron ores and other mineral resources remain unavailable for want of fuel. It is divided into two single-member constituencies. Castlebar is the county town.