Samuel Clemens (Mark Twain) is shown as arriving in the United States in 1877 on the Steamship Bermuda. The boat landed in New York and Clemens is listed as shown on the partial manifest image, in this post not under Mark Twain. These passenger manifests are part of the Ancestry Immigration Collection or can be viewed on microfilm via the National Archives. The advantage to using Ancestry is that they have indexed the records. Clemens must have been on a speaking tour in 1877 when he made this trip.
Of course, Mark Twain was born in Missouri and has already been located in several US census records.
