[Ger-Poland-Volhynia] Seeking information on likely Volhynian emigrants Matthias Stankevitz and Wilhelmina Nienicz or Nicniewicz

[Stephen H Karlson]

The individuals named in the subject line are two of my great-grandparents

The petition for naturalization of Matt Stankevitz gives his country of origin as Prussia.  His death certificate states he was born in Wittemberg, Germany (as in Martin Luther's theses).  He arrived New York in August 1888.  Wilhelmina's death certificate gives her place of birth as "Germania."

Both Matt and Wilhelmina were Baptists, they spoke Polish, and they were listed in Anuta's _East Prussians from Russia_ although the records and oral tradition we have in hand gives nothing about where in the German settlements they lived.

My questions:

1.  Because Matthias and Wilhelmina and some of their older children arrived prior to the opening of Ellis Island, any record of their arrival would be in an archive other than Ellis Island.  Which archives would be most likely to be useful in documenting their arrival in the States?

2.  I know the Germans kept reasonably good records (not as good as the Puritans, but pretty good by the standards of the day.)  What archives for Wittemberg would be most helpful?  Are there indices to German records available in US libraries or online?

Thanks for your advice

Stephen Hopkins Karlson