Austria–Switzerland border

Taming the Rhine

The Alpine Rhine flooded the valley again and again, worst of all in 1817, and floods came again in 1888. A treaty of 1892 between Austria and Switzerland set up the International Rhine Regulation, which straightened the river and began a long partnership between the two countries.^[2]

The border, though, was meant to follow the middle of the Rhine as it ran before the works. That is why it still loops along stretches of the Old Rhine, such as at Sankt Margrethen and Diepoldsau, marked by boundary stones, while elsewhere it runs down the middle of the straightened river. A treaty of 20 July 1970 replaced all earlier agreements and described the whole line and its marking.^[1]

Mountains and a lake

South of Liechtenstein the border follows the watershed of the Ill basin to Dreiländerspitz and then ridges and rivers to Piz Lad, where Austria, Switzerland and Italy meet. That tripoint dates only from the 1919 Treaty of Saint-Germain; before the First World War it lay above the Stelvio Pass.^[1]

At the northern end, no treaty has ever fixed the borders on the Upper Lake of Lake Constance. Switzerland says the border runs down the middle of the lake, Austria says the lake is a condominium shared by all the shore states, and Germany’s position is ambivalent. In 1984 the Austrian state of Vorarlberg declared the open lake part of its territory, with its sovereignty shared with the other shore states; its neighbours did not respond.^[3]

“…one of the only places in Europe where no borders have ever been demarcated between member states.”^[3]