For some time I have thought it odd that people writing about Mark Twain occasionally use the term "riverboat," although Mark Twain himself seemed to use only "steamboat." Did he _ever_ use the word "riverboat"? In a computer search of his texts, I found 273 instances of "steamboat" -- including "steamboating" and "steamboatman"), but not a single instance of "riverboat" -- including open compounds, such as "river boat". (These texts include all the books that Mark Twain published during his lifetime, most of A. B. Paine's editions, and a few miscellaneous writings.) I would like to hear from anyone who can document any instance of Mark Twain's using "riverboat" in his published or unpublished writings. (Incidentally, I didn't find the term in any of the speeches edited by Paine, but I would be inclined to be skeptical of the accuracy of any speech transcribed by someone else.)