In the biography for Mr Silverthorne, it was stated that he was born in Michigan.  This is proof that he was born in Ontario.  His family moved shortly thereafter to Michigan where he is recorded, age 3, in the 1880 census.

Name:   Spencer Victor Silver Thorn Silverthorne
Date of Birth:  17 Oct 1876, Gender:  Male
Birth County:  Middlesex, ONT, CAN
Father's name:  Daniel Silverthorne, Mother's name:  Elizabeth Johnson
Roll Number:  MS929_29