When we talk about The Census, we usually mean the statistical Decennial Census tables. Census also publishes subject-specific analytical reports and specialized studies to supplement the decennial statistical reports.
The good news: all Census publications are in the public domain and accessible online.
The bad news: Census reports differ in style, format, and substance every decade, so it can be hard to navigate Census reports if you're unfamiliar with these publications. Even other librarians find govdocs hard to navigate, calling the field "Arcane," "forlorn," and "intimidating." See citation below for more on this point.
In addition to statistical data, the census volumes will include small reports for each session, followed by very details statistics. Reports are usually several pages long. To find these reports, and their companion figures:
For specialized report NOT created for a specific decennial census, search Census as AUTHOR, use the second box as a keyword search, and limit publications to the time period of interest (Ex 1860-1890)
This approach works in WorldCat as well. Search Census as the Author, then add your topic as a keyword or subject. Limit the publication date range to the time period of interest. Do not limit to a specific year, but maybe 2 or 3 decades.
Start with Social Explorer, which has statistics from 1790-present, including 10-year, 5-year, 3-year, and 1-year survey data. It also includes some special report data. It will Not tell you how many college libraries existed in Virginia in 1860, but will tell you about state-wide literacy and education rates. ALSO, the answer is 18 college libraries, with about 67,150 volumes total; for that level of detail, we will need to go into the volumes themselves.
Using Social Explorer
Historical Census Data can also be downloaded as datasets through IPUMS and ICSPR
You can also use GoogleBook to find census reports, if you're looking for something Very specific.
To do this, use the Googlebook advanced settings and:
This is not an exhaustive way to search, but it can be a good starting point.
NOTE: the Census records for 1790 and 1800 have been lost for Prince William County