Tregeiriog is a village in Wrexham county borough, Wales.
It is situated within the LL20 postcode district, which is within the Llangollen post town.
LL20 is the only postcode district within the Llangollen post town.
The Llangollen post town is within the Llandudno postcode area.
Administrative Ward: Dyffryn Ceiriog/Ceiriog Valley
Administrative District: Wrexham
Country: Wales
UK Parliament: Clwyd South