Ponca, Nebraska. In the 1840’s, European-American settlers travelling westward to the Willamette Valley in the Oregon Country, or to the new Mormon Zion in Utah, had to first cross the Missouri River before setting out across the Great Plains. When they arrived on the river’s eastern shore, many of these settlers noted the river’s impressive width. As a result, many of them referred to the river as “The Wide Missouri.” Throughout the nineteenth century and into the twentieth century, the Missouri’s width below Sioux City, Iowa, averaged between 5,000 and 10,000 feet. But during the river’s annual floods, it spread out even further, sometimes expanding as much as ten miles across. The Army’s navigation channel shrank the river’s average width to only 739 feet. From Sioux City south, the once wide Missouri became a narrow, rock-lined ditch. Today, the navigation channel ends at river mile 753, which is at the foot of Ponca State Park. From there to Yankton, South Dakota, the river remains unchannelized (although many private landowners are riprapping their river frontages).
Looking down on the river from the high bluffs at Ponca State Park, the Missouri appears broad and milky brown. The Wide Missouri is back after a long absence.