The Ceiriog Valley or Dyffryn Ceiriog is the valley of the River Ceiriog in north-east Wales. It is also the name of a ward of the County Borough of Wrexham Until 1974 the valley was part of the traditional county of Denbighshire; then it became part of the short-lived county of Clwyd, which was abolished in 1996. Geographically, parts of the Ceiriog Valley extend into Shropshire, England. The Ceiriog Valley runs west to east, south of the Vale of Llangollen.