The Avre 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...

 and a left tributary of the River Eure

Eure River

The Eure is a river in northern France, left tributary of the Seine. It rises at Marchainville in the Orne département and joins the Seine near Pont-de-l'Arche...

.

The headwaters are in the Perche

Perche

Perche is a former province of northern France extending over the départements of Orne, Eure, Eure-et-Loir and Sarthe, which were created from Perche during the French Revolution.-Geography:...

 forest in Orne

Orne

Orne is a department in the northwest of France, named after the river Orne.- History :Orne is one of the original 83 departments created during the French Revolution, on March 4, 1790. It was created from parts of the former provinces of Normandy and Perche.- Geography :Orne is in the region of...

. It is 280m above sea level and joins with the Eure near Dreux

Dreux

Dreux is a commune in the Eure-et-Loir department in northern France.-History:Dreux was known in ancient times as Durocassium, the capital of the Durocasses Celtic tribe. Despite the legend, its name was not related with Druids. The Romans established here a fortified camp known as Castrum...

 and forms the border between the Eure

Eure

Eure is a department in the north of France named after the river Eure.- History :Eure is one of the original 83 departments created during the French Revolution on 4 March 1790...

 and Eure-et-Loir

Eure-et-Loir

Eure-et-Loir is a French department, named after the Eure and Loir rivers.-History:Eure-et-Loir is one of the original 83 departments created during the French Revolution on March 4, 1790 pursuant to the Act of December 22, 1789...

 départements.

The Avre is 80 km long and its watershed extends to 917 km². It flows through the Orne, Eure-et-Loir and Eure départments and historically forms part of the border of Normandy

Normandy

Normandy is a geographical region corresponding to the former Duchy of Normandy. It is in France.The continental territory covers 30,627 km² and forms the preponderant part of Normandy and roughly 5% of the territory of France. It is divided for administrative purposes into two régions:...

.