Census Bureau's "By Decade" website - includes a variety of publications, questionnaires, datasets, and more
Questions asked (see questionnaire)
Name of head of family; age; sex; race; foreigners not naturalized; slaves; industry (agriculture, commerce, and manufactures).
Social Explorer - remote access limited to UCSD affiliates
Find all 1820 census publications in the library catalog.
Census for 1820 [C 3.14:820/1 and C 3.14:820/1/reprint and HA201 1820]
Digest of accounts of manufacturing establishments in the United States, and of their manufactures [C 3.14:820/2/reprint]