The Alter Rhein is the old river bed of the Alpine Rhine in St. Gallen

Canton of St. Gallen

The Canton of St. Gallen is a canton of Switzerland. St. Gallen is located in the north east of Switzerland. It covers an area of 2,026 km², and has a population of . , the population included 97,461 foreigners, or about 20.9% of the total population. The capital is St. Gallen. Spelling...

 and Vorarlberg

Vorarlberg

Vorarlberg is the westernmost federal-state of Austria. Although it is the second smallest in terms of area and population , it borders three countries: Germany , Switzerland and Liechtenstein...

 in the Rhine Valley

Rhine Valley

The Rhine Valley is a glacial alpine valley, formed by the Alpine Rhine , i.e. the section of the Rhine River between the confluence of the Anterior Rhine and Posterior Rhine at Reichenau and its mouth at Lake Constance....

, which was cut off when the Rhine was straightened during the 20th century. These cut-off arms have become valuable recreational areas and a nature reserve.

In 1900, the short-cut at Fussach was completed. The old river course, from Höchst

Höchst, Austria

Höchst is a municipality in the district of Bregenz, Vorarlberg, Austria.-References:...

 and St. Margrethen

St. Margrethen

St. Margrethen is a municipality in the Wahlkreis of Rheintal in the canton of St. Gallen in Switzerland.-Geography:...

 to the village of Altenrhein in Tahl

Thal, Switzerland

Thal is a municipality in the Wahlkreis of Rorschach in the canton of St. Gallen in Switzerland.-History:Thal is first mentioned in 1163 as curtis tale....

 on the shore of Lake Constance

Lake Constance

Lake Constance is a lake on the Rhine at the northern foot of the Alps, and consists of three bodies of water: the Obersee , the Untersee , and a connecting stretch of the Rhine, called the Seerhein.The lake is situated in Germany, Switzerland and Austria near the Alps...

 forms the border between Austria

Austria

Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...

 and Switzerland

Switzerland

Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

. In 1906, the ("Rhine Valley Inland Canal") was dug, connecting Sennwald

Sennwald

Sennwald is a municipality in the Wahlkreis of Werdenberg in the canton of St. Gallen in Switzerland.-Geography:Sennwald has an area, , of . Of this area, 49.9% is used for agricultural purposes, while 31.5% is forested...

 to St. Margrethen

St. Margrethen

St. Margrethen is a municipality in the Wahlkreis of Rheintal in the canton of St. Gallen in Switzerland.-Geography:...

. In 1923, another short-cut was completed at Diepoldsau

Diepoldsau

Diepoldsau is a municipality in the Wahlkreis of Rheintal in the canton of St. Gallen in Switzerland.-History:Diepoldsau is first mentioned in 891 as Thiotpoldesouua. Schmitter is first mentioned in 1385.-Geography:...

, creating another dead branch, also named Alter Rhein.

The area between the Old and New Rhine forms the nature reserve Rhine Delta (not to be confused with the Rhine Delta

Rhine-Meuse-Scheldt delta

The Rhine–Meuse–Scheldt delta is a river delta in the Netherlands and Belgium formed by the confluence of the Rhine, the Meuse and the Scheldt rivers. The result is a multitude of islands, branches and branch names that may at first sight look bewildering, especially as a waterway that appears to...

in the Netherlands).