A coal mine disaster in 1856 resulted in 114 casualties, and the lack of payment of any compensation to the miners' families caused bitter feelings in the community.

Neighbouring settlements are Penygraig, Trealaw, Tonypandy, Dinas Rhondda, Llwyncelyn and Porth.

However, at the ensuing trial at the Spring Assizes in Swansea in 1857, the cases against two were dismissed, the judge directed the jury to discharge one of the others and advised them to acquit the remaining two, which they did.

Under the Local Government Act 1888, from 1889 to 1974 the Cymmer division elected one councillor to the Glamorgan County Council.

[7] Under the Local Government (Wales) Act 1994 the Rhondda Cynon Taf County Borough Council was established in 1996 and included the Cymmer electoral ward.

[9] This continued in May 2022 with the Labour candidates, Gareth Caple and Ryan Evans, retaining the seats.