It is named after the town of Cavan and is based on the historic Gaelic territory of East Breffny (Bréifne).

[2] Cavan borders six counties: Leitrim to the west, Fermanagh to the north, Monaghan to the north-east, Meath to the south-east, Longford to the south-west and Westmeath to the south.

Cavan shares a 70 km (43 mi) border with County Fermanagh in Northern Ireland.

[7] A large complex of lakes form in the north and west of Cavan into designated Specially Protected Areas (SPA); an example is Lough Oughter.

From around the thirteenth century the area (Cavan) was part of the petty kingdom of East Bréifne anglicized Breffny O'Reilly after its then ruling Gaelic family.

The growing influence of several monastic orders in the new diocese called Tir Briuin Breifne from the mid twelfth century with abbey remains existent in locations such as Drumlane and later Trinity Island.

During the sixteenth century in the reign of Queen Elizabeth I the county of Cavan was formed and transferred to Ulster from 1584, following the composition of Breifne.

[citation needed] Under James VI and I, from 1610 the Plantation of Ulster saw the settlement and origins of several new towns within the county that include Bailieborough, Cootehill, Killeshandra and Virginia.

The winter of 1847 is particularly noted for the high levels of deaths nationally caused by diseases such as typhus and cholera.

The famous ballad "By Lough Sheelin Side" is based on this event witnessed by the local Catholic priest.

However, when the Irish Unionist Party met on 9 June 1916, the delegates from Cavan learnt that they would not be included in any "temporary exclusion of Ulster" from Home Rule; they agreed only with very great reluctance.

[12] Cavan is divided into three local electoral areas: Bailieborough-Cootehill, Ballyjamesduff-Virginia and Cavan-Belturbet, which hold 18 county council seats in total.

The N3 is the longest route in Cavan, crossing the county for 60 km (37 mi) from the Meath border at Whitegate near Virginia and through Belturbet into Fermanagh.

The N16 begins in Sligo and ends at Blacklion in the far northwestern tip of Cavan, it crosses the county for roughly 7 km (4.3 mi).

The N87 road begins in Belturbet and passes through Ballyconnell and Swanlinbar before crossing into County Fermanagh where it becomes the A32.

In the mid-1850s the Midland Great Western Railway built a line between the Inny Junction in County Westmeath (along their expanding network which was eventually to reach Sligo) and Cavan town.

The railways were an important part of the economic development of Cavan and carried passengers and freight to all over Ireland.

The railways also helped the popularity of GAA in Cavan grow, spectators could travel easily between towns.

After World War II, due to the shortage of coal in the country, uneconomic lines were terminated.

Today however this is mainly confined to leisure craft on the River Erne and Shannon-Erne Waterway from Belturbet and Ballyconnell as well as for angling activities.

the 2016 census reported the county's most numerous non-Irish nationalities as UK, Poland and Lithuania respectively.

Agriculture is the largest industry in the county, especially dairy milk processing as well as pig and beef farming.

[27] There is a total farmed area of 144,269 hectares (356,500 acres) in the county, and there are approximately 219,568 cattle in Cavan.

Pig farming regulations have put pressure on the industry, which is highly dependent on affordable credit.

[29] Traditionally an agricultural economy, Cavan has since expanded in other industries, chiefly quarrying, energy production and manufacturing facilities.

[30][needs update] Peat cutting exists in the northwest of the county, in the Cuilcagh range.