Hi Ronald, In 1920 John and Ellen were living in Elk River, Clearwater Co., ID. John A., b. Sweden, 37 yrs old, laborer. Ellen R., b. Sweden, 30. Conrad W., b. MT, 5.
You already know about the 1930 Census. This is the most recent Census viewable by the public. The 1940 Census will be released in 2012.
A John August Johnson, Age-72 died 20 July 1955 in Spokane, Spokane Co., WA. Mother=Anna. Source: Washington State Digital Archives, www.digitalarchives.wa.gov/ .
You can request a copy of his obituary from a volunteer at Random Acts Genealogical Kindness, www.raogk.org, read instructions, choose Washington, choose Spokane Co.
OR Washington State Library, www.secstate.wa.gov/library/ask.aspx . They will search the newspaper microfilm for 60 minutes without charge. They will email what they do or don't find to you. Takes about two weeks.
Also his death certificate will contain more information. For information on how to order go to www.doh.wa.gov/EHSPHL/CHS/cert.htm .
You can search for Anna Ellen's death info at Washington State Digital Archives, www.digitalarchives.wa.gov/ . You have to search for each first name separately.
The Eastern Washington Genealogical Society should be able to research the marriages of Anna and Helen if they have the WA State Marriage Index on microfilm. They also may be able to provide more information on the family through the City/County Directories, scrapbooks, etc. Their web site is at www.rootsweb.ancestry.com/~waewgs/ . Successful Searching!