The National Archives and Records Administration houses over 21.5 million cubic feet of government documents including printed materials, films, maps, audio, and electronic records. Their online catalog allows researchers to search over 3.5 billion electronic records. Genealogists can find useful records like military documents, passenger lists, and census data. The document recommends two National Archives resources - the Archival Research Catalog for searching descriptions and digital copies of records, and the Access to Archival Databases for online searches of records including genealogy documents. Both sites provide guides and tutorials to help users navigate the large amounts of information.