Railroads from New York to St. Louis, 1867:
Scharnhorst ( The Life of Mark Twain: The Early Years, 1835-1871, page 383) has Twain entering St. Louis after a transfer of trains in Terre Haute. These seems unlikely as the only line to East St. Louis from the east in 1867 was the Ohio and Mississippi. The Indianapolis and St. Louis was the second line to reach St. Louis and it was not completed until 1870.