United States Citizenship and Immigration Services (USCIS) is the government agency under the Department of Homeland Security (DHS) that oversees lawful immigration into the United States. Additionally, the USCIS handles the naturalization process by which permanent residents and children of US citizen parents acquire US citizenship.

Following the Sept 11th, 2001 attacks, Congress passed the Homeland Security Act of 2002 which dismantled the old Immigration and Naturalization Service (INS) and reorganized its functions into three new agencies under a newly formed Department of Homeland Security. The USCIS was intially organized as the Bureau of Citizenship and Immigration Services (BCIS) but subsequently changed its name. The other two agencies are the Immigration and Customs Enforcement (ICE) and Customs and Border Protection (CBP). 

The chronology of the institution's history is as follows: ^[1]

1891 Office of Superintendent of Immigration created and placed in the Treasury Department

1895 Office of Superintendent of Immigration upgraded to Bureau of Immigration

1903 Bureau of Immigration transferred to the newly created Department of Commerce and Labor

1906 Naturalization Service created and Bureau of Immigration became the Bureau of Immigration and Naturalization

1913 Bureau of Immigration and Naturalization divided into separate Bureaus – the Bureau of Immigration and the Bureau of Naturalization – and placed in the new Department of Labor

1924 U.S. Border Patrol created within the Bureau of Immigration

1933 The Bureau of Immigration and the Bureau of Naturalization reunited into a single agency, the INS

1940 The INS transferred from the Department of Labor to the Department of Justice

2003 The INS was abolished and its functions placed under three agencies – USCIS, ICE and CBP – within the newly created DHS

1. ↑ USCIS website at http://www.uscis.gov