U.S. Federal Agencies and Aliens
Several U.S. government agencies deal with aliens as follows (not an all-inclusive list).
Department of State:
Issues "visas" and other travel documents which allow aliens to enter the United States.
Immigration and Naturalization Service
On March 1, 2003 the Immigration and Naturalization Service (INS) ceased to exist as such, and transitioned into the Department of Homeland Security. The customer service functions of the INS are now handled by the United States Citizenship and Immigration Services (USCIS). The enforcement functions of the INS are now handled by the Bureau of Immigration and Customs Enforcement (ICE) within the Directorate of Border and Transportation Security (BTS). Together these two agencies control the admission of aliens into the United States, and monitor the "status" of aliens present in the United States. ICE also deports aliens who are in the United States illegally or who have violated their "status" while in the United States.
Department of Labor
Approves "Labor Certifications" in the case of certain classes of aliens (e.g., H-1b nonimmigrants) which allow these classes of aliens to be employed in the United States by certain employers.
Bureau of Educational and Cultural Affairs of the Department of State
Known by the acronym ECA and formerly known as the United States Information Agency (USIA). Administers the J-1 Exchange Visitor Program in the United States, and facilitates educational and cultural exchange between the United States and other nations.
Department of Commerce
Facilitates and promotes trade and investment between the United States and other nations. The DOC often sponsors aliens to visit the United States for the purpose of training and commerce.
Social Security Administration
Issues social security numbers to aliens (generally to aliens who are allowed to be employed in the United States under the immigration laws), accounts for the Social Security credits earned by aliens in the United States, and administers social security benefits payable to aliens.
Internal Revenue Service
Administers the taxation of aliens who live in the United States or who have income which is sourced in the United States. Assists the Department of State and the Department of the Treasury to negotiate and administer tax treaties and other diplomatic conventions which affect taxes.