In the Kiso region, the protection and restoration of portions of the historic post towns on the old Nakasendo and Kisoji highways has preserved the townscape of the Edo period down to the present. Moreover, this area corresponds to the upper reaches of the Kiso and Shinano rivers, one of the largest river systems in Japan. In these river basins, citizens' participation in river basin management and cooperation between upper, middle, and downstream regions has taken place across prefectural boundaries. From the viewpoint expressed above, this study takes up the Kiso region, which unites the historical characteristics of the post towns (cultural environment) with the river basin (water environment) conservation and management activities, in an effort to better understand these characteristics.