Errigal-Trough was a village that spanned County Tyrone and County Monaghan. Samuel Lewis described it in 1837 as "a parish, partly in the barony of CLOGHER, county of TYRONE, but chiefly in that of TROUGH, county of MONAGHAN, and province of ULSTER, 3 miles (S.S.W.) from Aughnacloy, on the road to Emyvale, and on the river Blackwater; containing 9321 inhabitants."
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Errigal-Trough Wikipedia(Text) CC BY-SA