FamilySearch Research Wikis https://familysearch.org/learn/wiki/en/Main_Page (read the “Historical Geography” and “Maps” topics in all relevant jurisdictions)

England Jurisdictions 1851 http://maps.familysearch.org/

Description: https://www.familysearch.org/learn/wiki/en/England_Jurisdictions_1851

A Vision of Britain through Time www.visionofbritain.org.uk

ScotlandsPlaces http://www.scotlandsplaces.gov.uk/digital-volumes/published-gazetteers-and-atlases/hay-shennan-county-and-parish-boundaries-1892

The IreAtlas Townland Data Base http://www.thecore.com/seanruad/

Irish Place names http://www.irish-place-names.com/

Map Portals for British Isles Research – Selected Examples

Old Maps Online www.oldmapsonline.org World's largest portal to discovering online images of historical maps.

GENUKI http://www.genuki.org.uk/ [Search for map links at different jurisdictional levels, including counties.]

CindysList http://www.CyndisList.com (check the “Maps and Geography” categories in all relevant jurisdictions)

British Cartographic Society: http://www.cartography.org.uk/

Interactive Map Sites for British Isles Research – Selected Examples

England and Wales (see also England Jurisdictions 1851, above)

Bomb Sight: Mapping the WW2 London Blitz Bomb Census http://www.bombsight.org

e-mapping Victorian Cheshire http://maps.cheshire.gov.uk/tithemaps/

Locating London's Past http://www.locatinglondon.org/

London Low Life http://www.amdigital.co.uk/m-products/product/london-low-life/

(academic library subscriptions; check on-campus availability through a guest account)

London OS Five Feet to the Mile Sheets [NLS] http://maps.nls.uk/os/london-1890s/index.html

The Map of Early Modern London http://mapoflondon.uvic.ca/index.htm

Tracks in Time, The Leeds Tithe Maps Project http://tithemaps.leeds.gov.uk/

Mapping Shakespeare's London http://map.shakespeare.kcl.ac.uk/

Scotland

AddressingHistory http://addressinghistory.edina.ac.uk/

RCAHMS: PastMap https://www.historicenvironment.scot/archives-and-research/archives-and-collections/pastmap/ and http://pastmap.org.uk/

Ireland

Ask about Ireland – Griffith's Valuation www.askaboutireland.ie/griffith-valuation/

(The best current resource for free Griffith's Valuation maps and plans.)

Army Barracks of Eighteenth-Century Ireland https://barracks18c.ucd.ie/

Clare County Library http://www.clarelibrary.ie/eolas/coclare/maps/index.htm

Putting County Clare Surnames on the Map

http://irish-genealogy-news.blogspot.ca/2013/07/putting-clare-surnames-on-map.html

Cork Past & Present: Maps of Cork http://www.corkpastandpresent.ie/mapsimages/corkinoldmaps/

The Down Survey Project http://downsurvey.tcd.ie/

NLS: Explore georeferenced maps (choose Ireland as the category) http://maps.nls.uk/geo/explore/

Ordnance Survey Ireland – Historical Mapping http://maps.osi.ie/publicviewer/#V2,588882,739883,1,10

http://www.osi.ie/blog/genealogy/

Alan Godfrey Maps

http://www.alangodfreymaps.co.uk

Statements of Permissible Use – Selected Examples

NLS: Copyright – Map images http://maps.nls.uk/copyright.html

Digital Archive: Toronto Public Library – Public Domain Designation

http://www.torontopubliclibrary.ca/digital-archive/license.jsp

New York Public Library: http://www.nypl.org/blog/2014/03/28/open-access-maps

OpenStreetMap Wiki: Out-of-copyright maps (general information, not legal advice)

http://wiki.openstreetmap.org/wiki/Out-of-copyright_maps

Canadian Sites – Selected Examples

Toronto Public Library – Digital Archive: http://www.torontopubliclibrary.ca/digital-archive/

Archives of Ontario – Digitized Patent Plans: http://www.archives.gov.on.ca/en/about/patent-plans.aspx

University of Toronto Map & Data Library – Maps & Atlases: http://mdl.library.utoronto.ca/collections/maps-atlases

Ontario Historical County Maps Project: http://maps.library.utoronto.ca/hgis/countymaps/maps.html

The Canadian County Atlas Digital Project: http://digital.library.mcgill.ca/countyatlas/searchmapframes.php

Library and Archives Canada - Maps, Charts and Architectural Plans Collection:

http://www.bac-lac.gc.ca/eng/discover/maps-charts-plans/Pages/maps-charts-architectural-plans.aspx

Perth & District Historical Society – Historical Mapping Project: http://www.perthhs.org/

Note that in addition to the trench maps available on the NLS site, McMaster University also has a significant collection online: The Lloyd Reeds Map Collection: http://library.mcmaster.ca/maps/