All publications from economic censuses from 1967 onward are available online. Scanned images in PDF and other formats are available for publications from the 1967 to 1987 economic censuses via the search at archive.org, using terms like "1987 census of retail trade Virginia".
Collections of hard-copy printed reports are maintained at certain major libraries; and individual reports may be accessible through interlibrary loan.
The Census Bureau Library has print volumes of the economic census starting with the 1935 Census of Business through the 1997 Economic Census. The library is able to provide scans of selected pages. The library also has print copies of the County Business Patterns for 1948-1997. Reference librarians are available to consult with users by phone (301-763-2511) and e-mail (firstname.lastname@example.org).
When working with historical data you need to keep in mind such things as industry comparability, geographic changes, and changes to the scope of the economic census. Learn more about comparing historical data.