Father: Delos H. Sullivan (1864-1933)
Mother: Carrie Sullivan (born approx 1873 in Wisconsin)

Siblings
Fay William Sullivan (male born Sept 21, 1894 in Iowa) (linked)
Hazel E. (Sullivan) Paulson (born Dec 1897 in Iowa) (she married William Paulson on Feb 5, 1916 in Burleigh, North Dakota. She was 19 years old and he was 26 years old)
Ross Edgar Sullivan (born approx 1903 in Iowa) (linked)
Clara L. (Sullivan) (born approx 1905 in Iowa) (linked)
Blanch May Sullivan (born Oct 28, 1906 in Iowa and died Feb 29, 1912 in Faulk County, Iowa)
Ralph O. Sullivan (1908-1949) (linked)
Delos Sullivan (born approx 1911 in SD) (linked)
Charles Everett Sullivan (born July 31, 1912 in SD and died Susanville, CA on Feb 4, 1963)

Wife: Gertrude C. Sullivan (1907-1975)

Children:
Mildred E. (Sullivan) (Mrs. Herbert) Krees (born approx 1928 in MN) (still alive in 2006)
Orville Oscar Sullivan (1929-2006)
Joyce Kay (Sullivan) (Mrs. Robert Elmer) McLean (born Oct 23, 1931)
Delos E. Sullivan (1934-1994)
Gerald Donald Sullivan (born Jan 18, 1938 in Hubbard, MN to Oscar C. Sullivan and Gertrude Cunningham Sullivan - died July 23, 1998)
Ronald Jon Sullivan (1948-1963)
Robert Sullivan
Larry Sullivan (still alive in 2006)

1900 US Census shows the following in the household in Pleasant Valley, Fayette County, Iowa: Delos Sullivan (age 36), Carry Sullivan (age 27), Fay Sullivan (age 5), Oscar Sullivan (age 3) and Hazel Sullivan (age 2).

1910 US Census shows the following in the household in Emerson, Faulk County, SD: Deloo Sullivan (age 45), Carrie Sullivan (age 37), William F. Sullivan (age 15), Oscar C. Sullivan (age 14), Hazel E. Sullivan (age 13), Edgar R. Sullivan (age 7), Clara L. Sullivan (age 5), Blanch E. Sullivan (age 3) and Ralph O. Sullivan (age 1 year and 5 months).

1920 US Census shows the following in the household in Badoura, Hubbard County, MN: Delvs H. Sullivan (age 55), Carrie Sullivan (age 47), Oscar C. Sullivan (age 24), Ross E. Sullivan (age 17), Clara L. Sullivan (age 15), Ralph O. Sullivan (age 11), Charles E. Sullivan (age 9), Charles E. Sullivan (age 7) and Carol L. Paulson (age 3 years and 1 month -- granddaughter to Delvs -- born approx 1917 in MN).

Oscar & Gertrude married in this time period

1930 US Census shows the following in the household in Badoura, Hubbard County, MN: Oscar C. Sullivan (age 34), Gertrude C. Sullivan (age 22), Mildred E. Sullivan (age 2 years and 1 month) and Orville O. Sullivan (age 0). Oscar's birthplace is listed as Iowa with his father's birthplace as Iowa and his mother as Wisconsin.