Since 1875, Congress has regulated immigration to the United States. In 1952, Congress compiled the immigration laws and enacted the Immigration and Nationality Act of 1952 (INA). Congress has amended and added to the INA many times, including, but not limited to, in 1965, 1986 (with the Immigration Reform and Control Act of 1986), 1990 (with the Immigration Act of 1990), 1996 (with the Illegal Immigration Reform and Immigrant Responsibility Act of 1996), and 2001 (with the USA Patriot Act). The INA and its amendments appear in Title 8 of the United States Code. State governments are generally not part of the immigration puzzle.

The Department of Homeland Security ("DHS"), the Department of Justice ("DOJ"), and the Department of State ("DOS") administer and enforce the INA and its amendments using their own regulations. The Departments' regulations appear in various titles of the Code of Federal Regulations ("CFR"), including 6, 7, 8, 20-22,28,32,42 and 45. The CFR is arranged by subject title and generally parallels the structure of the United States Code. The USCIS provides online access to the applicable CFR titles.

Immigration Judges interpret and apply the Immigration and Nationality Act (Title 8, U.S. Code). The decisions of the Immigration Judges on the Board of Immigration Appeals ("BIA") regulate the actions of DHS. Decisions of the BIA are binding on all DHS officers and Immigration Judges unless modified or overruled by the Attorney General or a Federal court. The BIA is considered part of the Department of Justice. The USCIS provides online access to opinions of the BIA.

Federal Courts also interpret and apply the Immigration and Nationality Act and its numerous amendments (Title 8, United States Code). The decisions of the Federal Courts govern the actions of the Immigration Judges and the DOJ, DOS, and DHS. The official site for the United State's Courts provides links to each individual federal court. Published opinions of the Courts of Appeals and the Supreme Court can be found on their websites.

In 2002, Congress passed The Homeland Security Act of 2002 which, among other things, created the United States Citizenship and Immigrations Services (USCIS). On March 1, 2003, the, now former, Immigration and Naturalization Service (INS) transitioned into the USCIS. The priorities of the USCIS are to promote national security, continue to eliminate immigration case backlogs, and improve customer services.

Through a network of local offices, Application Support Centers, Service Centers, local area immigration services field offices, National Customer Service Call (NCSC) Centers, Forms Centers, and the Internet, USCIS processes all immigrant and non-immigrant benefits provided to visitors of the United States.

The USCIS' website is a comprehensive resource for anyone in need of information on U.S. Immigration law and procedures.

The Department of Justice, along with the Department of Homeland Security and the Department of State, administer and enforce the Immigration and Nationality Act and its amendments.

The Department of Justice, along with the Department of Homeland Security and the Department of State, administer and enforce the Immigration and Nationality Act and its amendments. The Department of Justice's website includes an "Immigration Information" section.

The U.S. Immigration and Customs Enforcement (ICE) is part of the Deparment of Homeland Security. ICE is charged with the responsibility of investigating and enforcing federal immigration laws, customs laws, and air security laws. ICE's website provides information about the agency as well as its successful actions.

The U.S. Customs and Border Protection (CBP) is part of the Department of Homeland Security. The CBP protects our borders. The CBP's website provides information on the agency and its efforts.