A historian is studying how waterways shaped the early development of South Dakota. She focuses on the river that flows through the state's center, supports several reservoirs, and helped establish the location of the capital city. Which river is she most likely researching?

The Missouri River runs through central South Dakota and is dammed to form several large reservoirs, including Oahe Reservoir near Pierre. Pierre, the state capital, is located along the Missouri River, so it is the river described. The correct choice is the Missouri River.

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