The Ill (all capitals: ILL) is a 72-kilometre-long (45 mi) tributary of the Rhine in the western Austrian state of Vorarlberg.

Ill
The Ill near Gisingen (district of Feldkirch).
The Ill near Gisingen [de; ru; uz] (district of Feldkirch)
Map
Location
CountryAustria
StateVorarlberg
Physical characteristics
Source 
 • coordinates46°52′9″N 10°6′32″E / 46.86917°N 10.10889°E / 46.86917; 10.10889 (Ill source)
 • elevation2,240 m (7,350 ft)
Mouth 
 • coordinates
47°17′57″N 9°33′31″E / 47.29917°N 9.55861°E / 47.29917; 9.55861 (Ill mouth)
 • elevation
1,811 m (5,942 ft)
Length72 km (45 mi)
Basin features
ProgressionRhineNorth Sea

It flows from the northern slopes of the Silvretta mountain range and then runs north-west through Vorarlberg. The Ill passes through the Montafon and Walgau [als; de; fr; nl] valleys and the town Feldkirch. It joins the river Rhine a few kilometers northwest of Feldkirch ("Illspitz"), at the border with Switzerland. The Ill has several dams with hydroelectric power stations.