The impression I gathered in my research, and try to make clear in my
writing on the subject, is that Clemens composed most of his best-known
works in Elmira and edited them while the family was at home in Hartford.  I
put it that way because he worked, as Kathy pointed out, wherever he was. In
truth, we have some pretty good paper-and-ink evidence of where he was when
he worked on his manuscripts.  So how one answers the question depends
largely on how one conceives of writing.  If one thinks of writing as
composition -- those hours of initial inspiration when the flood of words
overflows onto the page -- then Clemens did it predominately Elmira, in the
hilltop study as best we can tell.  If writing equals editing -- when the
flood is tamed into artful channels -- then he did it everywhere, but most
often when the family lived on Farmington Avenue.

Andy Hoffman