最后需要澄清一下,美国移民局就是移民局,它目前的称呼是“U.S. Citizenship and Immigration Services”,早先的“United States Immigration and Naturalization Service”已于2003年3月撤销了。
另外,英语中的“naturalization”其实就是入籍的意思,根据维基字典,“naturalization”是指给予居住者以本土出生之公民同等权利“The origin of the term ‘naturalization’ is that it gives to a resident alien almost all of the rights held by a natural-born citizen.”
至于“同化”“归化”的英语应该是“assimilation”。例如:
Cultural assimilation: the process whereby a minority group gradually adopts the customs and attitudes of the prevailing culture
Americanization (of Native Americans): cultural assimilation of Native Americans in the United States