The Immigration and Naturalization Service was the name of the federal agency responsible for overseeing all aspects of immigration services, but in 2003 the federal government created three new agencies that operate under the Department of Homeland Security, explains U.S. Citizenship and Immigration Services. As of 2015, U.S. Citizenship and Immigration Services, Customs and Border Protection, and Immigration and Customs Enforcement conduct the activities of the defunct Immigration and Naturalization Service.
An executive order created the Immigration and Naturalization Service in 1933 to investigate, prevent and deport illegal immigrants, says U.S. Citizenship and Immigration Services. The bureau worked closely with the FBI and the Department of Justice to prosecute cases that violated immigration laws.
U.S. Citizenship and Immigration Services administers immigration benefit applications, according to its website. It also provides information and research concerning the history of immigration in the United States, such as the name of the first naturalized U.S. citizen and the origin of the current civics test.
Customs and Border Protection is the law enforcement agency responsible for monitoring lawful travel while preventing dangerous people and materials from entering the country, as the agency's website details. Agents screen cargo, arrest illegal immigrants and seize illicit drugs.
The primary activity of Immigration and Customs Enforcement is enforcing immigration laws, according to the organization's website. Agents work to halt the exploitation of unauthorized workers and remove aliens engaged in illegal activities. This agency seeks to prevent terrorism and halt the smuggling of people and goods.