The Rhine forms a major part of the border between Germany and France. In the Upper Rhine Plain, the river runs between France’s Alsace region and Germany’s state of Baden-Württemberg.
The Rhine rises in the Swiss Alps and flows north through Switzerland, Germany, France, and the Netherlands before reaching the North Sea. Its international importance comes from both geography and history: for centuries, it served as a frontier, trade route, and strategic waterway.
The modern France–Germany border is not entirely formed by the Rhine. Farther north, the border leaves the river and continues across land before reaching the Moselle near the France–Germany–Luxembourg tripoint. That detail explains why the Rhine is the standard quiz answer but not the complete description of the entire national border.
The Rhine is sometimes confused with the Danube or Elbe, both important German rivers. Neither forms the principal France–Germany boundary.