Columbia subject headings:
Harvard subject headings:
Border security--Canada--History--20th century--Case studies.
Border security--United States--History--20th century--Case studies.
Canadian-American Border Region--History--20th century--Case studies.
Cities and towns--Canadian-American Border Region--History--20th century--Case studies.
World War, 1914-1918--Social aspects--Canada--Case studies.
World War, 1914-1918--Social aspects--United States--Case studies.
Princeton subject headings:
Border security--Canada--History--20th century--Case studies.
Border security--United States--History--20th century--Case studies.
Canadian-American Border Region--History--20th century--Case studies.
Case studies.
Cities and towns--Canadian-American Border Region--History--20th century--Case studies.
World War, 1914-1918--Social aspects--Canada--Case studies.
World War, 1914-1918--Social aspects--United States--Case studies.