There have been 3 major waves of immigration. The newest has been the Latin wave (or "New World Immigrant", see #3 below), but it must be understood in context of the other two. Much of the unite/divide is a socio-economic push/pull relationship (because the countries are so close) and a case of identity (race, ethnicity, region):
1. The standard immigrant story of escaping the Old World and assimilating to the New World and its dominant culture:
•Eastern and central Europeans and Jews (late 1800s)
•Asian Americans (late 21st century)
Sometimes called “model minorities” for conformity to American economics.
2. The minority narrative:
Not an immigrant story of voluntary participation and assimilation but of involuntary contact and exploitation, resisting assimilation, and creating an identity more less separate from the mainstream.
3. The New World immigrant:
Constitutes the largest wave of contemporary immigration, combines immigrant and minority narratives, voluntarily immigrating from the Caribbean/West Indies but often with experiences of involuntary contact and exploitation by the US in other countries, or identification with minorities through the color code.
So says sociologist professor Craig White:
[Another in-between variation is the shift of the United States from a "White & Black nation” to a "Brown nation" defined by growing Hispanic populations and intermarriage.]