Later groups of immigrants, like the Italians, Polish, and the Jewish were treated very poorly when they came to the US in the 1900s. Many immigrants were funneled into urban ghettos, areas with poor living quarters resulting in high levels of death and disease. By the 1920s, the United States was reeling from its involvement in World War I and entered a period of isolationism. This was marked partly by a withdrawal from world affairs, but also a negative view on immigrants entering the country. In the early 1920s, the US passed the Immigration Quota Act which restricted the number of immigrants allowed to enter the country. President Warren G Harding's election based on a "return to normalcy" reflected the idea that Americans disliked immigrants who maintained cultural and linguistic ties to their homelands.
The majority of the indigenious peoples who came in contact with the Spaniards died from foreign disease(s). Some of those diseases were smallpox, influenza, measles, and chickenpox.
