Kevin--

Your request for tracing his use of the word "nigger" in his works made me
recall an editorial he wrote in the Buffalo _Express_ titled  "Only a
Nigger" in which he criticizes the execution of the wrong man for a crime in
the South, after which the officials responsible for the miscarriage of
justice simply shrugged it off with the title of the piece.
This piece is just one reason for those interested in Twain to get a hold of
Joe McCullough and Janice McIntire-Strasburg's edition _Mark Twain at the
Buffalo Express_ (disclosure, I reviewed it for the Twain Web in 1999).

This piece also suggests a meaningful source for Huck's similar response to
Aunt Sally when she asks if any was hurt during his fabricated steamboat
accident.  His response "No'm, just a nigger," has been variously
interpreted as signalling Huck's racism on the one hand to a signal that he
understands how he should play the point to this audience.

LH