Columbia subject headings:
Drug control--United States.
Illegal immigration--United States.
Law enforcement--United States.
Noncitizens--United States.
Harvard subject headings:
Border patrols--United States
Border patrols--United States.
Illegal immigration--Government policy--United States.
Immigration enforcement--United States
Noncitizens--Government policy--United States
Ports of entry--United States.
Smuggling--United States--Prevention.
Princeton subject headings:
Drug control--United States.
Illegal aliens--United States.
Law enforcement--United States.