Columbia subject headings:
Harvard subject headings:
Mexico--Boundaries--United States.
Mexico--Foreign economic relations--United States.
Rio Grande Region (Colo.-Mexico and Tex.)--Economic conditions.
Rio Grande Region (Colo.-Mexico and Tex.)--Social conditions.
Rio Grande Region--Economic conditions.
Rio Grande Region--Social conditions.
United States--Boundaries--Mexico.
United States--Foreign economic relations--Mexico.
Princeton subject headings:
Mexico--Boundaries--United States.
Mexico--Foreign economic relations--United States.
Rio Grande Region--Economic conditions.
Rio Grande Region--Social conditions.
United States--Boundaries--Mexico.
United States--Foreign economic relations--Mexico.