Monmouthshire (/ˈmɒnməθʃər, ˈmʌn-, -ʃɪər/ MON-məth-shər, MUN-, -sheer), also formerly known as the County of Monmouth (/ˈmɒnməθ, ˈmʌn-/ MON-məth, MUN-; Welsh: Sir Fynwy), was one of the thirteen counties of Wales that existed from 1536 until their abolition in 1974. Located in the south-east of Wales, on the border with England, its area now corresponds approximately to the present principal areas of Monmouthshire, Blaenau Gwent, Newport and Torfaen, and those parts of Caerphilly and Cardiff east of the Rhymney River.
The eastern part of the county was mainly agricultural, while the western valleys had rich mineral resources. This led to the area becoming highly industrialised with coal mining and iron working being major employers from the 18th century to the late 20th century. Its five largest towns were Newport, Cwmbran, Pontypool, Ebbw Vale and Abergavenny.