Samuel Clemens does appear in the following censuses that are available at ancestry.com: 1850 - Hannibal, Missouri 1860 - St. Louis, Missouri 1870 - Buffalo, New York 1880 - Hartford, CT 1900 - Hartford, CT 1910 - Redding, CT The Redding census sheet is interesting because the census taker has dated it one day after Clemens's death, April 22. However, user comments on ancestry regarding this sheet indicate the actual census was taken on April 15, 1910. If you do not have a full subscription to ancestry.com it may be difficult to zero in on these sheets. However, if you are a subscriber, there are a list of SUGGESTED RECORDS for each individual that lead directly to the other census sheets. His name has often been misspelled by transcribers and other researchers have provided corrected spellings and identifications. There are a number of amusing transcriber errors related to some of these census sheets. For example, the 1870 census sheet has Clemens's occupation as "clerk in dry goods" rather than "Prop. daily paper". The 1910 census sheet has his occupation transcribed as "Waiter" "hardware st" rather than "Writer" "Humorist." As to the 1840 census -- Samuel Clemens is not listed by name, but his father John Marshall Clemens and household members are in the Mason Township, Marion County, Missouri census. As another Forum member, Bob Stewart, recently pointed out to me, there is only one slave listed in the family household -- a female between the ages of 10 - 23. Barb