Archives in the United States:

http://archiwa.pilsudski.org/index.php

http://www.piasa.org/archives.html

Archives in Poland:

http://szukajwarchiwach.pl/

https://www.bu.umk.pl/Archiwum_Emigracji/

Useful links (archival sites):

Detroit Area Polonia and the city of Hamtramck
Holocaust Archive/Oliver Lustig Photographs
Immigration History Research Center
Lattimer Massacre Article
Krakow Painted By Light: Archival Photographs
Kwasniewski Photographic Collection
Lattimer Massacre
Library of Congress: Polish Declaration of Admiration & Friendship for the United States Archive (1926)
Polish American Cultural Center Philadelphia
Polish American Journal
Polish Music Center at USC
Polish Genealogical Society of America
Polish Institute of Arts & Sciences of America, Inc.
Polish Music Center
Polish Room At Lockwood Library - SUNY Buffalo
Polish Roots
Project Inposterum
Virtual Tour of Old Hamtramck
Warsaw Uprising