River History Series Kicks Off as a Part of Water Trails Regional Planning Effort in Des Moines 1/5/2016 9:36:00 AM View Count 4815 The confluence of the Des Moines and Raccoon rivers has attracted humans for at least 7,200 years, from hunter-gatherers living in small houses along the river, to prehistoric mound builders, to soldiers exploring the area, to a growing metropolis.