Kongeå

The river Kongeå (in German Königs Au) defines the border between Northern and Southern Jutland in Jutland in Denmark. It rises southeast of Vejen and Vamdrup and after about 50 kilometres (31 mi) flows into the North Sea north of Ribe.

In the Middle Ages it was called Skodborg Å after the royal castle Skodborghus that was at a crossing south of Vejen. For centuries, there was a customs border near Kongeå that separated the Kingdom of Denmark from the duchy of Schleswig. From 1864 to 1920 it was (except for near the North Sea) the border between Denmark and Germany.