In the two centuries after the founding of the American Republic, a population already multiethnic because fantastically more so. Territorial expansion through conquest, purchase, and annexation added to the origin diversity, but the primary source (lowed from a massive infusion of immigrants from almost everywhere. If for no other reason, their acculturation demands attention for the light it sheds on the character of the United States. An issue is what is meant to be an American in a nation whose history has denied its people the bond of a common paternity.
It is enough to say that more immigrants, more different kinds of immigrants, have entered the United States than any other country in modem history. The conditions that led them to leave their native homelands varied: overpopulation, economic opportunities, famine, drought, war, religious persecution, political oppression. Whatever the push that set them in motion, the pull that lured them to America was the promise of a fresh start. Much the same reasons explain why newcomers are still coming.
It is argued that far from putting down roots only in the East, as is sometimes supposed, immigrants dispersed throughout most of the country. Immigration was not merely a big-city phenomenon. Immigrants and their children at the end of the 19 century constituted the majority in the still heavily rural and small town states of Minnesota, Dakota, Montana, Arizona, Wyoming, Utah, Nevada and California. Immigrants played an important role in shaping American nation. In connection with that question we can conclude that the interplay between ethnic diversity and national unity is of lasting importance.
A common American nationality was shaped thanks to the adoption in 1790 of the uniform naturalization procedure by the first Congress. This statute was revised in 1802 and it still remains in force. Its main goal is to help the foreign-born acculturate as quickly as possible. This law defines the terms by which newcomers with a bewildering variety of backgrounds are able to join' the host people as citizens of a republic. The 1802 act set a five-year residence requirement, which was judged sufficient for immigrants to familiarize themselves with American life, to show intent to remain here, and to demonstrate "good moral character".