Hi & thanks for the response! I have checked the Border Crossing records but no luck. I've searched online (Ancestry and Family Search) in Ontario and Michigan for a death record for Mary Boyd nee Gibson but I haven't contacted the Vital Statistics Registry offices. I'll try that. I've also searched the Canada Census 1901 and USA Census 1900 but no luck. I've found some but not all of the children in the US and Canada but can't find Mary with any of them. The children were:
Elizabeth m'd Edward Atkinson: moved to Michigan @1880 and lived in Detroit
Henry: moved to Detroit by 1900. Last census I found him was 1910.
Michael: moved to Croswell, MI by 1880 but moved back to Middlesex, Ontario by 1895. Can't find him in the 1901 or 1900 Census.
Anna Maria: m'd 3 times, stayed in Middlesex, Ontario
Melinda: m'd Alexander Frank Plant & moved to Massachusetts
Robert: can't locate after 1881 in London, Ontario
William George: moved to Lambton Co., Ontario
Ada Jane: m'd twice, Scarcliff and Holloway; Living in Detroit in 1888 at the time of her marriage; No other records
Benjamin: can't locate after 1881 in London, Ontario
John Albert: Lived in St. Clair Co., MI from 1900 to 1940
Edgar Flannery Boyd: lived in St. Clair Co., MI from 1900 to 1917 (death)