Q. If I’m in the United States and I’m quoting a person in Canada, do I say he is from “city, county,” or “city, Canada?”
A. Supply as much information as you think the reader you are addressing will need or appreciate, which sometimes might include only the city (Toronto), sometimes the city and province (Hamilton, Ontario), and sometimes all that plus “Canada” (Swan River, Manitoba, Canada). For instance, young children might need more information than adults. Or for locations in British Columbia, readers in faraway Texas might need more help than those in nearby Seattle. As for the county, you can add it if you think it will be meaningful to your discussion, but that seems unlikely in most contexts.