In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Portskewett like this:
PORTSCUETT, Portskewit, or Porth-is-Coed, a parish in Chepstow district, Monmouth; on the Severn'sestuary, the Julian way, and the Great Western railway, at the Junction of the Bristol and South Wales Union railway, 4¼ miles S W by S of Chepstow. It has a station with telegraph at the railway junction; and its post town is Chepstow. ...
Acres, 1, 779; of which 720 are water. Real property, £2, 110. Pop., 175. Houses, 36. The property is all in one estate. The living is a rectory, united with the rectories of St. Pierre and Sudbrook, in the diocese of Llandaff. Value, £402.* Patron,Lewis, Esq.
Portskewett is now part of Monmouthshire district. Click here for graphs and data of how Monmouthshire has changed over two centuries. For statistics about Portskewett itself, go to Units and Statistics.
GB Historical GIS / University of Portsmouth, History of Portskewett in Monmouthshire | Map and description, A Vision of Britain through Time.
Date accessed: 25th April 2017
Click here for more detailed advice on finding places within A Vision of Britain through Time , and maybe some references to other places called " Portskewett ".