Hello all
I've been looking for large, high quality resolution scans of maps of cities in north american in the 1880-1920 area, specifically cities in the United States and Canada outside of Toronto (have a good resource for that one.)
Wasn't sure if this would apply here or in Maps or in MapPorn, but figured this was the safest bet.
Have a look at davidrumsey.com, at chicagoinmaps.com, and at the new collection recently put up at New York Public Library.
Historic USGS maps are available through the USGS Historic Topos page and enter the placename. This should take you right to it: http://store.usgs.gov/b2c_usgs/usgs/maplocator/(ctype=areaDetails&xcm=r3standardpitrex_prd&carea=%24ROOT&layout=6_1_61_48&uiarea=2)/.do Click on the red marker and it will show you which maps can be downloaded. You add it to your "download cart," the proceed to download the (rather large) file.
For Prince Edward Island, you can check out the Island Imagined site, put together by UPEI and the Island's Public Archives.
Historical maps of Nova Scotia are available at the Nova Scotia Public Archives.