In tracing my 1st cousin 4 times removed, Marian F. Key, I came across the following census information:

1910 US Census - Precinct 10, Prowers County, Colorado
NA Series: T624 Roll: 123 Page: 141 Sheet: 6B ED: 138 Date: 12 May 1910
Alexander D. Mavis, Head M W 63 M2-1 Yr. OH PA OH General Farmer
Marion Mavis, Wife F W 39 M2-1 Yr. 3 Children, 2 Living IA Unk Unk None
Nora Mavis, Adop. Daughter F W 12 Single IA OH IA None
Carl Mavis Adop. Son M W 8 Single IA OH IA None

1920 US Census - 1042 Robinson Avenue, San Diego, San Diego County, California
NA Series: T625 Roll: 131 Page: 164 Sheet: 2B ED: 278 Date: 3 January 1920
Marian Mavis, Head Rents F W 48 Married IA IN PA None
Nora Adams, Daughter F W 21 Married IA IA IA None
Lewis Harris, Son M W 19 Single IA IA IA Poultry Raiser Farm
Julie Mavis, Daughter F W 9 Single CO IA IA None
James Mavis, Son M W 9 Single CO IA IA None

I noticed that Marian listed that she was "Married" in the 1920 census, not widowed or divorced. However, I have not found Alexander in the 1920 census. I am not entirely sure that Julie is the correct name of their daughter - the census image that I had was very dark at that point in the page.

According to the California Death Index, Marian was born 19 September 1871 (Wapello, Louisa County, Iowa, daughter of Darius and Maria (Lyman) KEY), and died in San Diego on 19 January 1943. Her first husband was Charles S. HARRIS, and together they had three children. Nora Harris was shown as married to an Adams in the 1920 census (not listed there, possibly military?), but probably appears as Norah Eyman in the California death index. I have found nothing more on the Mavis children.

Any information on Alexander, his wives or children would be appreciated. I also have some informaion on Marian's family if anyone is interested.