Shinano River

The Shinano River (信濃川 Shinanogawa) is the longest river in Japan. It flows from Nagano Prefecture to Niigata Prefecture in Japan. It is 367km long (228 mi) and has 11,900 km² watershed (third largest in Japan). It is called the Chikuma River (千曲川 Chikumagawa) in Nagano Prefecture.

The river rises from Mount Kobushi on the border of Saitama, Yamanashi and Nagano, and flows to the northwest and meets the Sai River from Matsumoto. Kawanakajima (川中島), the junction of the Chikuma and the Sai, is the historic site where the Battles of Kawanakajima broke out. It turns to the northeast and falls into the Sea of Japan at Niigata City.

In 1922, the Ōkōzu Canal (大河津分水路 Ōkōzu Bunsuiro) was built to defend Niigata from floods. It enabled the Niigata Plains to be filled with rich rice fields.