International research tools
Familysearch
Historical records (i.e. vital records, census, naturalization, etc.) https://www.familysearch.org/search
Online records collection https://www.familysearch.org/catalog/search
Obtaining the information about naturalization, social security number and vital records
United States:
Passengers Manifests and travel information
Argentina:
CEMLA (Argentina) http://cemla.com/buscador/
United States:
Compilation of various passenger manifests https://stevemorse.org/
Ellis Island https://www.libertyellisfoundation.org/
Castle Garden http://www.castlegarden.org/
https://www.familysearch.org/wiki/en/U.S._Immigration_%E2%80%93_After_1820
Just How Were Passenger Manifests Created? by Sallyann Sack-Pikus
Immigrant Records: More Than Just Ship Passenger Arrival Lists by Elizabeth Burnes
Manifest markings
Red Star Passenger Lists https://www.gjenvick.com/PassengerLists/BrowseByYear/index.html
"Trains and Shelters and Ships" © Aubrey Newman Paper presented at a seminar under the auspices of the Jewish Genealogical Society of Great Britain, April 2000. http://www.jewishroots.uct.ac.za/trains.htm
https://www.gjenvick.com costs of emigration in the late 1800s but there is a lot of information at this site
http://www.ballinstadt.de the Emigration Museum BallinStadt, Hamburg
Immigration agencies in Poland (in Polish)