Although the 1790 and 1800 census were strictly population counts, the returns for Virginia have not survived.
A substitute for the 1790 census was constructed from the 1782-1785 state tax enumerations of the following counties that are now part of West Virginia:
These were published as:
United States Bureau of the Census. Heads of Families at the First Census of the United States Taken in the Year 1790 -- Records of the State Enumerations: 1782-1785, Virginia. (Washington: Government Printing Office, 1908. Reprinted: Baltimore, 1966 and 1970; Bountiful, Utah, 1978.)
The counties not included in that publication were subsequently covered in the following book:
Augusta B. Fothergill and John Mark Naugle. Virginia Tax Payers, 1782-87. (Richmond, 1940. Reprinted: Baltimore, 1966.)