The regulation of immigration and naturalization in the United States is primarily a federal power. This power is granted to the federal government through the Constitution. The main federal agency responsible for this regulation is the United States Citizenship and Immigration Services (USCIS), which is part of the Department of Homeland Security. State governments, on the other hand, have limited powers when it comes to immigration and naturalization. While states may enact certain laws and policies related to immigration, they must still operate within the framework of federal immigration laws and regulations.
