Castleblayney
| Castleblayney Baile na Lorgan | |
|---|---|
| Town | |
| West Street | |
| Coordinates: 54°07′12″N 06°44′20″W / 54.12000°N 6.73889°W | |
| Country | Ireland | 
| Province | Ulster | 
| County | Monaghan | 
| Elevation | 104 m (341 ft) | 
| Population  (2022) | 3,926 | 
| Eircode routing key | A75 | 
| Telephone area code | +353(0)42 | 
| Irish Grid Reference | H824199 | 
| Year | Pop. | ±% | 
|---|---|---|
| 1831 | 1,828 | — | 
| 1841 | 2,134 | +16.7% | 
| 1851 | 2,077 | −2.7% | 
| 1861 | 1,822 | −12.3% | 
| 1871 | 1,809 | −0.7% | 
| 1881 | 1,810 | +0.1% | 
| 1891 | 1,721 | −4.9% | 
| 1901 | 1,576 | −8.4% | 
| 1911 | 1,692 | +7.4% | 
| 1926 | 1,550 | −8.4% | 
| 1936 | 1,725 | +11.3% | 
| 1946 | 1,769 | +2.6% | 
| 1951 | 2,173 | +22.8% | 
| 1956 | 2,143 | −1.4% | 
| 1961 | 2,127 | −0.7% | 
| 1966 | 2,083 | −2.1% | 
| 1971 | 2,395 | +15.0% | 
| 1981 | 3,473 | +45.0% | 
| 1986 | 3,035 | −12.6% | 
| 1991 | 2,938 | −3.2% | 
| 1996 | 2,808 | −4.4% | 
| 2002 | 2,936 | +4.6% | 
| 2006 | 3,124 | +6.4% | 
| 2011 | 3,634 | +16.3% | 
| 2016 | 3,607 | −0.7% | 
| 2022 | 3,926 | +8.8% | 
Castleblayney (/ˌkæsəlˈbleɪni/; Irish: Baile na Lorgan) is a town in County Monaghan, Ireland. The town had a population of 3,926 as of the 2022 census. Castleblayney is near the border with County Armagh in Northern Ireland, and lies on the N2 road from Dublin to Derry and Letterkenny.