Leitrim, derived from the Irish 'Liathdroim' , meaning the grey hillridge, is in the north of the Republic of Ireland on Donegal Bay and covers 407,260 acres or 614 sq. miles.

The county is nearly divided into two parts by Lough Allen with the mountains in the north and wet lowlands in the south.

The Shannon River forms the southwestern boundary of the county.

The surface is extremely uneven, being composed of bogs and high mountains, which afford sufficient herbage for the breeding of cattle. The valleys are fertile and watered with rivulets Potatoes, barley, rye, and wheat, are cultivated in small quantities, and oats in greater abundance

The mountains contain inexhaustible stores of lead, iron, and copper ores. Coal is mined in the Lough Allen Basin. Linens and coarse woolens are manufactured for domestic use.

The O'Rourke clan ruled most of the county in Celtic times but were supplanted by the Normans and later by the English, who imposed a policy of land confiscation and plantation on Leitrim at the beginning of the 17th century.

Towns such as Carrick-on-Shannon, Manorhamilton and Jamestown were established and fortified during this time. Emigration from famine times onwards caused the population to dramatically drop from a high of 155,000 in the early 19th century to around 25,000 today.