Tone River
Under the Tokugawa Shogunate, the course of the Tone River was diverted in 1654 to prevent flooding in Edo. The new mouth of the Tone River was moved from Edo Bay to north of the Bōsō Peninsula, which greatly hindered river transportation. The "daimyō" of Sekiyado Domain, Itakura Shigetsune, took advantage of this situation to construct a canal joining the Tone River with the Edogawa River at Sekiyado, which greatly shortened the voyage and enhanced the revenues of his domain.