1880 census of Elliott Co., Ky, Martinsburg precinct, enumerated 7 June, lists on p. 11 as family #78:
Thornberry, Isaac, 31, farmer, b. Ky Ky Ky; Mary S., wife, 24, b. Ky Va Va; Laura J., 6, dau; George W., 4, son; John M., 2, son. All children born Ky Ky Ky.

1900 census of Elliott Co., Ky, Sandy Hook precinct, enumerated 15 June, lists on p. 14A as family #213/216:
Thornsberry, Isaac, 51, b. Apr 1849, Ky Ky Ky; Mary S., wife, 45, b. Oct 1854, Ky Va Va; Gorge W., son, 24, b. Oct 1875; John M., son, 22, b. Aug 1877; Charley V., son, 18, b. Dec 1881; Milfred D., son, 16, b. Sep 1883; Nora Ethel, dau, 15, b. May 1885. All born Ky Ky Ky.

There is probably one more child in the family. The census images for this entire precint chop off the last two lines of each page. This family is at the bottom of the page, and the top of the next page starts with a wife named Rutha Fannin, 6 children, then household #215/218 headed by George Thornsberry age 45, indicating that line 49 of p. 14A belonged to the Isaac Thornsberry family, and line 50 contained the husband of Rutha Fannin heading household #214/217.