Ellis Island/Immigration laws.
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* The first federal immigration law is passed in 1790-
* 1875- prostitutes, criminals & lunatics denied US entry. 
* 1903-Anarchists are denied admittance 
* 1907-denied entry to physical and mental disabilities & children arriving without adults.
* Immigrants are Jews,Poles, Hungarians, Czechs, Serbs, Slovaks and Greeks, Syria, Turkey & Armenia
http://www.history.com/topics/ellis-island
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Arrival at the Island and Initial Inspection-The two agencies responsible for processing immigrants at Ellis Island were the United States Public Health Service & the Bureau of Immigration (later known as the Immigration and Naturalization Service-INS)

The two main reasons why an immigrant would be excluded were if a doctor diagnosed that the immigrant had a contagious disease that would endanger the public health or if a legal inspector thought the immigrant was likely to become a public charge or an illegal contract laborer.
https://www.libertyellisfoundation.org