Columbia subject headings:
Border security--Mexican-American Border Region.
Mexican-American Border Region--Economic conditions.
Mexican-American Border Region--Politics adn government.
Mexico--Relations--United States.
United States--Relations--Mexico.
Harvard subject headings:
Mexico--Foreign relations--United States.
Mexico--Politics and government--21st century.
United States--Foreign relations--Mexico.
United States--Politics and government--21st century.
Princeton subject headings: