How long did it take mark twain to write huck Finn?

some sources such as wikipedia say seven years. i have also heard fifteen years. in the book, before the introduction, there is a timeline which states "nearly ten years." i guess no one knows for sure! some sources such as wikipedia say seven years. i have also heard fifteen years. in the book, before the introduction, there is a timeline which states "nearly ten years." i guess no one knows for sure!