The Sauer is a river

River

A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...

 in France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 (Alsace

Alsace

Alsace is the fifth-smallest of the 27 regions of France in land area , and the smallest in metropolitan France. It is also the seventh-most densely populated region in France and third most densely populated region in metropolitan France, with ca. 220 inhabitants per km²...

) and Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 (Rhineland-Palatinate

Rhineland-Palatinate

Rhineland-Palatinate is one of the 16 states of the Federal Republic of Germany. It has an area of and about four million inhabitants. The capital is Mainz. English speakers also commonly refer to the state by its German name, Rheinland-Pfalz ....

). A left tributary of the river Rhine, its total length is about 70 km. Its upper course, in Germany, is called Saarbach. Its source is in the Palatinate forest, near the French border, south of Pirmasens

Pirmasens

Pirmasens is a district-free city in Rhineland-Palatinate, Germany, near the border with France. It is famous for the manufacture of shoes. The surrounding rural district was called Pirmasens from 1818 until 1997, when it was renamed Südwestpfalz....

. It flows into France near Schœnau

Schœnau

Schœnau is a commune in the Bas-Rhin department in Alsace in north-eastern France.-References:*...

, and continues through Wœrth

Wœrth

Wœrth or Woerth is a commune in the Bas-Rhin department in Alsace in north-eastern France.It lies north of Strasbourg. Wœrth is known for the Battle of Wœrth, in the initial stage of the Franco-Prussian War in August 1870.-References:*...

 and north of Haguenau

Haguenau

-Economy:The town has a well balanced economy. Centuries of troubled history in the buffer lands between France and Germany have bequeathed to Haguenau a rich historical and cultural heritage which supports a lively tourist trade. There is also a thriving light manufacturing sector centred on the...

. It flows into the Rhine in Seltz

Seltz

Seltz is a commune in the Bas-Rhin department of the Alsace region in north-eastern France. It is located on the Sauer river near its confluence with the Rhine, opposite the German town of Rastatt.-History:...

, opposite the mouth of the Murg

Murg

The Murg is a river and right tributary of the Rhine in Baden-Württemberg, Germany.-Source:The river has numerous tributaries and is known as the Murg only from the point of confluence of the rivers Rechtmurg and Rotmurg in the community of Obertal, a part of Baiersbronn...

.