I received this from another mailing list. "From the NARA publication, c. 1982, p. 38" Census years: 1790 thru 1820... Census taken as of: First Monday in August of given year. Census years: 1830 thru 1880...Census taken as of: 1 June of given year Census year 1890...Census taken as of: First Monday in June 1890 Census Year: 1900...Census taken as of: 1 June 1900 Census year: 1910...Census taken as of: 15 April 1910 Those were the only years posted on the mailing list. Hope it helps someone Julia