What made immigration different in the time between 1860 and 1920 than in previous years?

Immigrants that arrived in America between 1860 and 1920 were different than in previous years due to their country of origin.  Before 1860, most immigrants to the New World were from countries in Western Europe:  England, Scotland, Ireland, France, Spain, Portugal, and Germany.  Many immigrants that arrived during prior to 1860 came for religious and economic freedom.  

New ideologies, revolutions and wars in the second half of the 19th century resulted in "new" immigrants arriving from countries in Eastern Europe:  Germany, Austria, Hungary, Czechoslovakia, Italy, Serbia, Greece, Poland, and Russia.  In 1848, the last of the absolute monarchs in Europe struggled to maintain control as political revolutions rocked the continent.  New political ideologies such as Socialism and Marxism often led to protests and unrest as workers challenged the status quo in an industrialized Europe.  Wars between Germany, Austria, and France displaced many people as borders changed frequently.  It was a time of uncertainty and violence, leading many "new immigrants" to try to improve their lives in America.  So many immigrants fled Europe that Ellis Island was built in New York City to process the new arrivals to the United States.  (See image:  Courtesy of history.com)