If you are seeking basic information and are not in the library: Decennial Census -- History -Measuring America: The Decennial Censuses From 1790 to 2000
Index of Census Questions 1790-2010
Census Questionnaires 1790-2010
If you are seeking more detailed information, see:
Encyclopedia of the U.S. Census from the Constitution to the American Community Survey. M. J. Anderson, C. F. Citro, & J. J. Salvo (eds.) Thousand Oaks, CA : CQ Press, 2012.
Measuring America: The Decennial Censuses From 1790 to 2000. J.G. Gauthier. Washington, D.C.: U.S. Dept. of Commerce, Economics and Statistics Administration, U.S. Census Bureau, 2002.(includes questionnaries from every census)
For a history of the census as both a political and a bureaucratic process:
The American census: a social history. Margo J. Anderson. New Haven: Yale University Press, c2015.
Firestone HA37.U55 A53 1988
Dubester’s U.S. census bibliography with SuDocs class numbers and indexes. Kevin L. Cook. Englewood, Colo.: Libraries Unlimited, 1996.
Z7553.C3 C66 1996
State censuses; an annotated bibliography of censuses of population taken after the year 1790 by States and Territories of the United States. Prepared by Henry J. Dubester. Washington, D.C., U.S. Govt. Print. Off. 
Stokes: Z7554.U5 U63 1948
State census records. Ann S. Lainhart. Baltimore, Md.: Genealogical Publishing, 1992.
Z5313.U5 L37 1992
Bureau of the Census catalog of publications, 1790-1972. United States Bureau of the Census, 1974.
See also: U.S. Census Guide
Historical Statistics on the Foreign Born Population of the United States: 1850-2000 Bureau of the Census
Tables include country of birth, mother tongue, race, age and sex at the national level. Also provides nativity data (foreign or native born) for metropolitan areas, counties, and 50 large urban areas.
Encyclopedia of American Immigration. Salem Press, 2010.
Very brief entries for every state, with a few references.
Trustee Reading Room Reference (DR): JV6465 .E53 2010.
A Companion to American Immigration. Edited by Reed Ueda. Malden, MA ; Oxford : Blackwell Pub., 2006.
Donald E. Stokes Library (SPR): JV6465 .C74 2006.
Family Search, a service of the Church of Latter-Day Saints, offers digitized collections of birth, marriage, and death records, records of military service, and probate records (wills and estates).