Ajo, Arizona: Heavy-duty, non-biodegradable canteens—occasionally insulated with clothing or blankets to prevent chafing—scatter the desert in the Tucson sector of the United States border with Mexico.
Sindo Ferry passengers have their passports checked and their luggage x-rayed before they board, but they are divided about how meaningful national boundaries are.
Since ancient times, border walls have simultaneously assuaged and stoked our fears of outsiders. But a history of walls can't tell the full story of civilization.