[Ger-Poland-Volhynia] NEUSTADT; POLAND (Schlock, Zimmers)

[Efhensel at aol.com]

Dear Friends,
 
Ludwig Schlock (Schlack, and other spellings), came to the USA in 1888,  he 
was born in 1864 in what he terms as
 
"Neustadt in Poland";  re renounced Nicholas  II, Emperor of Russia. So 
this place must be in the former Russian part of  Poland.
 
Which Neustadt could this be?
What is todays name of it?
Where is it located?
 
Any hints are welcome.
 
Thanks,
 
Eckhard (Hensel)