This Swiss 50-centime stamp, issued in 1992, commemorates the 100th anniversary of the Internationale Rheinregulierung (International Rhine Regulation), marking a century of cooperative management of the Rhine River between Switzerland and Austria (1892–1992). Designed by Arnold Wittmer and printed by Courvoisier, the stamp features a graceful tern soaring over a stylized map of the Rhine, symbolizing environmental restoration and cross-border unity in river engineering and ecology. The modern, geometric design reflects both the technical and natural balance of the Rhine’s regulation project.