The River Clwyd (Welsh: Afon Clwyd) is a river in Wales that rises in the Clocaenog Forest (grid reference SJ045535) 5 mi (8.0 km) northwest of Corwen.
It flows due south until, at Melin-y-Wig, it veers north-eastwards, tracking the A494 and passing through Derwen, Llanelidan, Pwllglas and Llanfair Dyffryn Clwyd to Ruthin. Here it leaves the relatively narrow valley and enters a broad agricultural vale, the Vale of Clwyd (Welsh: Dyffryn Clwyd). Just south of Denbigh, it is joined by the River Clywedog. This substantial tributary also has its source in the Clocaenog Forest but drains out to the east and north of the forest and passes through Cyffylliog, Bontuchel and Rhewl before its confluence with the main river.
Then the Clwyd meanders northwards through the fertile Clwyd valley to St Asaph. Two miles north of St Asaph, the river is joined by a tributary as large as the main river, the River Elwy. In normal flows at low tide, the waters of these two rivers can be seen flowing side by side down the river with little mixing.
Clwyd (Welsh pronunciation: [ˈklʊɨd]) is a preserved county of Wales, situated in the north-east, bordering England with Cheshire to its east, Shropshire to the south-east, and the Welsh counties of Gwynedd to its immediate west and Powys to the south. It additionally shares a maritime border with the metropolitan county of Merseyside along the River Dee. Between 1974 and 1996, it was a county with a county council, and it was divided into six districts. It is named after the River Clwyd, which runs through the region. It was also a Royal Mail postal county before the postal county scheme was abolished in 1996. Clwyd County Council was based in the county town of Mold.
From the late 1950s, the radical reform of local government in Wales was considered more pressing than that in England, due to the small size of many of the existing authorities, especially the upper tier county councils. The Local Government Commission for Wales set up in 1958 was the first to recommend wholesale amalgamation of the administrative counties outside Glamorgan and Monmouthshire, with extensive boundary changes; however the then Minister of Housing and Local Government Sir Keith Joseph decided not to accept the report, noting that county amalgamations in England had been highly unpopular when proposed.