Columbia subject headings:
Harvard subject headings:
Border patrols--United States
Border security--United States
United States--National Guard--Operational readiness.
United States. Bureau of Customs and Border Protection
Princeton subject headings:
Illegal aliens--Prevention--Government policy--United States.
U.S. Customs and Border Protection--Rules and practice.
United States--Boundaries--Management.
United States--National Guard--Rules and practice.