Thanks, Doug. Yes, I'm using the Canadian Archives site, too. Awesome resource, since they have indexes and images of the census microfilms and FamilySearch only has the index files.
And now, serendipity - as McCallum is my paternal grandmother's maiden name. I have not done as deep research on that side of the family. Blanche Florence McCallum was my paternal grandmother, daughter of Eugene N McCallum (b 1884) and Florence Kelsey (b 1883). I have located Eugene's 1905 S. Dakota census card (father born in Maine, mother in Vermont), and Florence in her family's 1900 census in Missouri. That's as far back as I've gone so far. Oh, and I've found one sister for Eugene, Violet, likely born in 1897, as she was 8 years old in 1905 in S. Dakota.