The family in 1900 was living in Belford, Auora, SD.
Some of the family in 1910 was living in Belford.
Andy Nelson, head, b. SD, 24, farmer home farm.
Senna, sister, b. SD, 19.
Mary, sister, b. SD, 9.
Nels and Martin were living in Belford with the Fraser family.
Nels nelson, hired hand, b. SD, 20, both parents born Denmark.
Martin Nelson, hired hand, b. SD, 17, both parents born in Denmark.
In 1920 Andrew and family were living in Cooper, Aurora, SD.
Andrew nelson, head, b. SD, 35, both parents born Denmark, farmer.
Jessie, wife, 33.
Irene, 3 9/12ths.
In 1930 Andrew and family was living in Bristol, Aurora, SD.
Andrew C. Nelson, b. SD, 45, both parents born Denmark, farm laborer.
Jessie B., wife, b. SD, 43.
Edna C., b. SD, 16.
Irene M., b. SD, 14.
Violet E., b. SD, 12.
Donald A., b. SD, 10
C. Owen Spencer, boarder.
Andrew in 1940 was living in Lone Pine, Lane, OR.
Thomas Gunson, b. IA, 50, education=5th grade, nurseyman farmer.
Sena, wife, b. SD, 49, educ=8th grade.
Mary, b. SD, 25, educ=high school 4 yrs.
John, b. SD, 16.
Doris, b. SD, 13.
Rodger, b. SD, 8.
Betty Jane, b. SD, 5.
Andrew C. nelson, b. SD, 54, farmer. In 1935 he was living in Plankington, Aurora, SD.
I found an
Andrew C. nelson
Born: abt. 1886
Died: Multnomah Co., OR, 3 Nov 1963
Wife: Josephine per death cert #15656.
Source: Oregon Death Index 1898-2000.
I'm NOT positive this is your Andrew.
I found most of the other family members on family trees at ancestry.com. Most libraries provide access to Ancestry.
Andrew C. nelson, b. Denmark 30 April 1853 died 5 Aug 1902, Aurora Co., SD
Mattie Christina (Katie) Jenson Nelson
Born: 6 March 1861, Denmark
Died: 16 Dec 1922, Aurora Co., SD
Source: heibuet Family Tree. I encourage you to double check or verify anything you find on a family tree. South Dakota doesn't publish much information. Death records weren't required on a state-wide basis until July 1905. I'd check Aurora County Recorder for Andrew's death info. I'd check South Dakota Health Dept., http://doh.sd.gov/VitalRecords/genealogy.aspx
Anna Christina Nelson b. 10 Nov 1888, Aurora Co., SD died 2 Sept. 1981, Norwalk, Los Angeles, A. She married Anson Nicholas Nagel 13 Sept. 1911 in Aurora Co.
The nelse-Provost family tree has a picture of Gensine/Senna and a picture of Marazza (Mary) Nelson.
The Hirsh family tree has:
Emma L. Nelson
Married: 18 Dec 1913, Sanborn, SD
Henry H. Wolfe.