town (“community”), Rhondda Cynon Taff (Rhondda) county borough, historic county of Glamorgan (Morgannwg), Wales, on the River Cynon. The community dates from the Middle Ages. Its Saint John's Church was built about 1189. Aberdare's main growth in the 19th century was based on iron ore (first ironworks 1799) and coal, particularly steam coal for export after 1836. A branch (1811) of the Glamorganshire Canal and, later, railways provided outlets to the South Wales coast. In the 20th century the town's iron industry ceased, and coal mining declined in the vicinity. Aberdare now serves as the chief shopping and service centre for the Cynon valley. Modern industries include the manufacture of cables, smokeless fuel, and, at Hirwaun to the northwest, light engineering and electrical products. Pop. (2001) 31,705.