Formed from an ancient glacial lake, the Red River Valley is famous for its flat landscape and fertile soil. Perhaps less known is that it is also one of the most flood-prone areas in the U.S.

Cutting through the valley, the northward flowing Red River winds its way from Breckenridge, Minn., to Lake Winnipeg in Canada, establishing most of the border between North Dakota and Minnesota. As snow melts in the valley’s southern regions each spring, the flows of the Red River and its tributaries are impeded by ice dams to the north, causing water to surge across low-lying farmland and towns. Flooding has been calamitous, particularly for the cities of Fargo, N.D. and Moorhead, Minn., which straddle the river. Many years, an all-hands-on-deck call has gone out to the community, launching an emergency sandbagging offensive to keep rising floodwaters at bay.