County Monaghan is a county in Ireland. It is in the province of Ulster and is part of Border strategic planning area of the Northern and Western …County Monaghan is a county in Ireland. It is in the province of Ulster and is part of Border strategic planning area of the Northern and Western Region. It is named after the town of Monaghan. Monaghan County Council is the local authority for the county. The population of the county was 65,288 according to the 2022 census.