Search the database CQ Researcher for articles on Census counts.
For books, it is best to use the Advanced keyword search, the term "1990 Census" and limit it to the Collection:
Paley Stacks. Otherwise, the results will be overwhelming:
4) Most of the last two Census' are available online. The 2000 Census of Population and Housing is the latest decennial census in print at call number HA201.122 .C464 2003 on the second floor East side of Paley Library.
Microfilm copies of United States decennial census publications, 1790-1970 are on the Ground Floor of Paley in boxes with the number Micro- film 3500 above the PER cabinets. The reel guides are at the ends of the rows.