Mogami River

This first-class river flows through Yamagata Prefecture. With its source at Mt. Nishi-Agatsuma on the border with Fukushima Prefecture, it courses through the nearby basin and across the Shonai Basin before emptying into the Sea of Japan. Approximately 80% of the prefecture's population inhabits the Mogami River basin (including tributaries such as the Sagae River), so it has played a key role in water transport since ancient times. The culturally important waterway has appeared many times in song. Matsuo Basho's haiku about it reads The swift Mogami River gathers summer rain.