In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Garth like this:
GARTH, a hamlet in Llanfabon parish, Glamorgan; on the river Taf, 5 miles NNW of Caerphilly. Real property, £10, 346; of which £8, 184 are in canals, and £30 in quarries. Pop., 1, 209.
A Vision of Britain through Time includes a large library of local statistics for administrative units. For the best overall sense of how the area containing Garth has changed, please see our redistricted information for the modern district of Rhondda; Cynon; Taff. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Garth and units named after it.
GB Historical GIS / University of Portsmouth, History of Garth, in Rhondda; Cynon; Taff and Glamorgan | Map and description, A Vision of Britain through Time.
Date accessed: 22nd May 2013
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Garth".