This marriage is recorded in Morgan Co. marriage book 1 as “Obediah Day” and Cynthia Fannin, on 28 Oct 1840 by John Williams. The “Obediah” is probably just a clerk’s error; Rowan County records are all consistent in using Jedediah or Jeddiah. See, e.g., the birth records for Eli and John C.

1860 census of Rowan Co., Kentucky, records as family #21:
Jedediah Day, 39, farmer, blind; Cynthia Ann, 38; William, 17; David, 15; Jacob, 13; Sarah, 11; Daniel, 8; Eliza, 3; John C., 1 year. All born Kentucky. (Eliza should be Eli; probably the census taker misheard it. Toddler boys wore dresses in those days.)

1870 census of Rowan Co., Kentucky, Christy Creek precint, lists as family #16:
Day, Jedediah, 49, farmer; Cynthia, 48; William, 25, blind; David, 23, blind; Jacob, 21; Sarah, 19, blind; Daniel, 16; John, 11; Isaac, 6; Susan, 3. All born Kentucky.

1880 census of Rowan Co., Kentucky, Christy Creek precinct, lists as family #395:
Day, Jedediah, 59, farmer; Cynthia, 58, wife; William, 37, son, musician; David, 35, son, musician; Jacob, 33, son; Sarah, 30, dau; Isaac, 17, son; Susan, 13, dau. All born Ky Ky Ky.

William, David, Jacob, and Sarah all have a checkmark in the blind column.

Also living with the family are two boarders and two servants: Polly Williams, 81, boarder, widowed, Ky NC NC; Polly A. Kidd, 25, boarder, Ky Ky Ky, died this year; Ellen Davis, 19, servant, Ky Ky Ky; William Fults, 17, servant, Ky Ky Ky.

1900 census of Rowan Co., Kentucky, Hoggstown precinct, page 243A, lists as family #217:
Day, Jedediah, 79, farmer, b. Nov 1820, Ky Va Ky, widowed; William, son, fiddler, 58, b. May 1842; Thomas, Sherdan, boarder, 23, b. Feb 1877; Cora, boarder’s wife, 18, b. Feb 1882, married 5 years, mother of 2 children, 2 living; Anna B., boarder’s dau, 3, b. July 1896; Sherman L., boarder’s son, 3/12, b. Mar 1900; McBrayer, Ollie, boarder, 15, b. June 1884, widowed, mother of 2 children, 2 living; James L., boarder’s son, 1, b. Sep 1898; Lula M., boarder’s dau, 5/12, born Jan 1900; Thomas, Edda (male), boarder, 18, b. Sep 1881. All born Ky Ky Ky except Jedediah. (Ollie McBrayer and Cora Thomas are Jedediah’s granddaughters, so some of the other boarders may be related as well.)