Columbia subject headings:
Harvard subject headings:
Mexico--Economic conditions.
Rio Grande River (Tex.)
Rio Grande Valley (Colo.-Mexico and Tex.)--Economic conditions--19th century.
Rio Grande Valley (Colo.-Mexico and Tex.)--History.
Princeton subject headings:
Rio Grande Valley (Colo.-Mexico and Tex.)--Economic conditions--19th century.
Rio Grande Valley (Colo.-Mexico and Tex.)--History.