His ages varies considerably in the census records, so be careful not to confuse him with any of the following other William and/or Green Deharts of Patrick and Floyd counties:

William Green Dehart born Feb 1866, son of William T. Dehart & Louisa Dillon, who married Lutitia Carter

William Green Dehart born Oct 1866, son of John W. Dehart & Mahala Shelor, who married Mary “Mollie” S. Weaver

William D. Dehart born June 1866, son of Robert Dehart & Mariah E. Taylor, who married Mahala A. Nolan

Abram Green Dehart born Feb 1867, son of Eleazer Dehart & Mary J. Houchins, who married Josephine E. Boyd

David Green Dehart born Aug 1868, son of Eli Dehart & Leah Owens, who married Rosa A. Whitlock

William A. Dehart born ca 1874, son of Elam G. Dehart & Nancy E. Houston, who married first L. R. Harris and second Susan.

William Woolwine Dehart born 26 Jan 1875, son of Stephen H. Dehart & Isabell Woolwine, who married Eliza Ann Booth

I’ve tried to enter enough source records to help distinguish all the above individuals.

Since Nettie was born after June 1880, and married before 1900, she will not appear in any census with her parents.

1900 census of Floyd Co., Virginia, Burks Fork district, enumerated 11 June, lists on p. 5B as family #85:
Dehart, William G., 23, b. Oct 1876, farmer; Nettie, wife, 21, b. Feb 1879, married 5 years, mother of 2 children, 2 living; Callamsy, dau, 2, b. Dec 1896; Ellena, dau, 3/12, b. Feb 1900. All born Va Va Va.

Note that the reported age and birthdate for Callamsy are not consistent.

1910 census of Patrick Co., Virginia, Smith River district, enumerated 4 May, lists on p. 11B as family #197/199:
DeHart, William G., 36, farmer; Nettie, wife, 30, married 14 years, mother of 7 children, 6 living; Callie, dau, 12; Lener, dau, 10; Laura, dau, 8; Roosevelt, son, 6; Edwin, son, 3; Dorothea, dau, 8/12. All born Va Va Va.

1920 census of Floyd Co., Virginia, Burks Fork district, enumerated 7 Jan, lists on p. 4A as family #51/52:
Dehart, William G., 48, farm laborer; Nettie, wife, 41; Callie, dau, 22; Lina, dau, 19; Laura, dau, 17; Rosevelt, son, 15; Edwin, son, 13; Dortha, dau, 10; Jessie, son, 8; Bryan, son, 6; Mary, dau, 2 0/12. All born Va Va Va.

The preceding household is that of William’s father and two youngest sisters.

1930 census of Floyd Co., Virginia, Burks Fork district, enumerated 21 April, lists on p. 9B as family #172/173:
Dehart, Green, 61, age at first marriage 22; Nettie, wife, 49, age at first marriage 16; Roosevelt, son, 23; Edwin C., son, 21; Jessie G., son, 18; Marry E., dau, 13. All born Va Va Va.