I'm somewhat confused. For years, I have only heard one origin for Samuel Clemens' pen name, Mark Twain. This was, of course, the Mississippi River origin. However, in his book, "On the Road with Mark Twain in California and Nevada", George Williams III states that the true origin of the name was from his telling a bartender in Nevada to "Mark Twain" on his tab. Which of these origins is true? I would really like to know which one it is. Sincerely, Rob McMonigal