I received an email from someone that is very knowledgeable about license plates in my area.
"Thanks for the link to that most unusual plate. If it is indeed Ontario, it is nothing like anything else the province has issued. I am not aware of any places having Dray plates from that long ago. Even Toronto isn't known to have had them that far back, and if they were issued, it's likely a few would have turned up by now. I find it possible, though unlikely, this is an Ontario plate, especially for a smaller town like Cobalt. Finally the dies on this plate do not suggest any kind of manufacture in Ontario. To me, this looks more likely to be something from Minnesota, Michigan or NY. A bordering state would be plausible - someone moving to Ontario, no longer needing the plate and turfing it away. Also consider that any cross-border cartage company would have required a license for the US side of the business, if one was mandated. Unfortunately this plate could remain a mystery for a very long time - without any photos or documentation it may never be resolved as there's nothing on the plate to suggest where it is from. Sorry that I could not be of any real help in this situation. - Joe Sallmen(Author of 'Ontario License Plates - A Century of History' published in 2003/04)."
The mystery continues..