The Thur is a river in north-eastern Switzerland. The length is 131 kilometres (81 mi). Its source is near the mountain Säntis in the southeast of the canton of St. Gallen. In this canton it flows through the Toggenburg region and the town of Wil. After Wil it flows through the canton of Thurgau and its capital Frauenfeld. The final 19 kilometres (12 mi) of the river are in the canton of Zurich. It flows into the river Rhine on the border with Germany, south of Schaffhausen.