Columbia subject headings:
Mississippi River Valley--Social life and customs.
Mississippi River--Description and travel.
Harvard subject headings:
Authors, American--19th century--Biography
Mississippi River Valley--Social life and customs.
Mississippi River--Description and travel.
Pilots and pilotage--Mississippi River.
Steamboats--Mississippi River.
Twain, Mark, 1835-1910--Travel--Missisippi River.
Princeton subject headings:
Mississippi River Valley--Social life and customs.
Mississippi River--Description and travel.