Son of Joel Blackwell II (1790–1847) and Virginia "Jenny" Skinner (1807–1870).

Married Sarah Elizabeth Herrin on 3 Dec 1853, Union Co., KY.

Children:
Sarah Jane Blackwell (1854-1925) m. James P. Dixon in 1877
Lucy M Blackwell (1856)
Martha Tilda Blackwell (1861-1948) m. Clinton Cruse
Atley Boyd Blackwell (1863-1928)
Fannie Frances Blackwell (1866-1930) m. Robert Dillback
Allen Blackwell (1869)
William Danial Blackwell (1870-1939)
Jeff Blackwell (1873-1935)
Cordia Belle Blackwell (1884-1963) m. Omer Vaughn

1850 Census (Dist. 2, Union Co., KY)
Jane Blackwell 43 (Mother)
James Blackwell 22 ****
Jesse Blackwell 20
D H Blackwell 19
Edmond Blackwell 14
Rebecca Blackwell 8
Malvina Blackwell 20

1860 Census (P.O. Morganfield, Union Co., KY)
James Blackwell 33
Elizabeth Blackwell 23
Sarah J Blackwell 5
Lucy M Blackwell 3
Beverly E Blackwell 9/12
Jane Blackwell 53 (Mother)
Rebecca E Blackwell 18
Jno Herrin 29
Jno Dill 22

1870 Census (Dist. 5, Webster Co., KY)
J S Blackwell 44
Sarah E Blackwell 35 TN
Virginia Blackwell 63 (Mother)
Sarah J Blackwell 15
Lucy M Blackwell 13
Martha M Blackwell 9
Atley B Blackwell 6
Francis M Blackwell 4
William D Blackwell 7/12

1880 Census (Clayville, Webster Co., KY)
James Blackwell 53 Self (Head)
Elizabeth Blackwell 44 Wife
Atley B. Blackwell 16 Son
Fannie Blackwell 14 Daughter
Allen Blackwell 11 Son
Danial Blackwell 9 Son
Jeff Blackwell 6 Son
Clinton Cruse 20 Son-in-law
Martha Cruse 18 Daughter

1900 Census (Clay, Webster Co., KY)
Martha Cruise 38 Head widowed
Larence B Cruise 19 Son
Edna T Cruise 18 Daughter
Effie Cruise 14 Daughter
Tom Baker 24 Boarder

James S Blackwell 73 Head
Sarah E Blackwell 66 TN Wife (married 1853)
Cordie B Blackwell 16 Daughter
Francis M Dillback 14 Daughter
James Dillback 15 Grand Son (Grandson)
Sada Dillback 8 Granddaughter
Linna Dillback 5 Granddaughter

James and Sarah died btw, 1900 and 1910