In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Dolgarrog like this:
DOLGARROG, a township in Llanbedr-y-Cennin parish, Carnarvon; on the river Conway, 7 ½ miles S of Conway. Pop., 134. Houses, 27. A mountain torrent here, descending from Llyn-Cwlyd, makes two grand falls, jointly 180 feet.
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 Dolgarrog has changed, please see our redistricted information for the modern district of Conwy. More detailed statistical data are available under Units and statistics, which includes both administrative units covering Dolgarrog and units named after it.
GB Historical GIS / University of Portsmouth, History of Dolgarrog, in Conwy and Caernarvonshire | Map and description, A Vision of Britain through Time.
Date accessed: 31st August 2015
Click here for more detailed advice on finding places within A Vision of Britain through Time, and maybe some references to other places called "Dolgarrog".