Individual records from the Federal population censuses are confidential for 72 years, by law (Title 44, U.S. Code). Microfilm copies of the original population schedules, from 1790 to 1930, have been released and are available at the National Archives in Washington and other libraries around the country. Columbia University does not have copies of the schedules, but they are available at two places in the city: the New York Public Library's Schomburg Center for Research in Black Culture, and the National Archives and Records Administration's Northeast Region Office. Information on both is below. Butler Reference has catalogs to the schedules, also lilsted below.
It may be useful to begin a search for individual census records with the National Archives web page, Census Records. Additionally, the following specific catalogs and reference tools are available: