Mary may actually be the daughter of John A. Black. She was listed in the 1870 census as Mary Clark, age 4 months, but Martha (Riddle) Clark and John Black were already living together. I do not know exactly when John B. Clark died. Mary was definitely raised as a Black.

She is probably the child listed as “America, age 8” in the 1880 census. (No child named Mary nor any other daughter over the age of 3 appears in the household in that census.) See census notes for John A. Black for details.

Rowan Co. marriage book A, p. 67, records marriage of John Kegley and Mary Black on 2 Feb 1884.

1900 census of Rowan Co., Ky, Hoggtown precinct, enumerated 17 June, lists on p. 8B as family #140/141:
Kegley, John, 38, b. Nov 1861, Ky/Va/Va; Mary, wife, 30, b. 1870; Ida, dau, 14, b. Sep 1885; Sarah J, dau, 9, b. Jan 1891; Harvy, son, 7, b. Feb 1893; William, son, 6, b. Feb 1894; Frank, son, 5, b. May 1895; Noah, son, 2, b. Mar 1898. All but John born Ky/Ky/Ky.

1910 census of Rowan Co., Ky, Hoggtown prec., E.D. 156, page 5B, taken 21 Apr, records as family #90:
Kegley, John, 48, farmer, Ky Va Va; Mary, 41; married 26 years, 9 children, all living; Harvy (or Harry), 18; William, 16; Frank, 14; Noah, 12; Everet, 10; Ora, 2. All born in Kentucky except John's parents.

1920 census of Wyoming Co., West Virginia, Center district, enumerated 30 Jan, lists on p. 6A as family #102:
Kegley, John R., 58, foreman at tram road, b. Ky Va Va; Mary, wife, 51; Frank, son, 23; Evert, son, 18; Luster, son, 15; Ora, son, 14; Ota, son, 6. All except John born Ky Ky Ky.

They are living in a little cluster of Rowan and Elliott Co. families. The preceding three households are their son Noah with his wife Della (daughter of Walter Crose), Robert Conn (son of William H. Conn) with his wife Rissie Lewis, and Robert’s brother Marcus Conn with his wife Rosa Thomas. Also on the same page, at household #93, is the family of Joseph Quesenberry (son of Lawson) and his wife Susie Wilson.

1930 census of Rowan Co., Ky, Haldeman precinct, enumerated 15 April, lists on p. 2B as family #32:
Kegley, John, 68, age at first marriage 20, laborer at brickyard; Marry, wife, 61, age at first marriage 13; Oda, son, 16; Lester, son, 24, age at first marriage 23; Dessie, dau-in-law, 20, age at first marriage 18; Ora, son, 23, age at first marriage 23; Irean, dau-in-law, age at first marriage 18. All born Ky Ky Ky. (Lester and Ora are also recorded as laborers at the brickyard.)