Today while reading some old Michiagn History Magazines I found in a 1946 magazine, a review of an article in the Canadian Historical Review about Canadians joining the Union army during the Civil War.
"How British Soldiers were lured into the United States from Canada for service in the northern armies during the Civil War is described by Marquerite B. Hamer in an article of the June 1946 issue of the Canadian Historical Review. According to a British military dispatch quoted by the author " Any detachment near Detroit will melt away." Michigan regiments befitted from recruiting across the border to the extent of 19,341 recruits"
Depending on the source, Michigan provided 90,000 men during the Civil War. If 19,341 Candi an crossed the border to join Michiagn registrants, then over 21% of the 'Michigan' men were Canadians. Please note I have not read the article in the Canadian Historical Review and can make no comment on Hamer's information.