 Since the beginning of the 20th century , the Missouri River has been extensively engineered for water transport purposes , and about 32 percent of the river now flows through artificially <unk> channels . In 1912 , the USACE was authorized to maintain the Missouri to a depth of six feet ( 1 @.@ 8 m ) from the Port of Kansas City to the mouth , a distance of 368 miles ( 592 km ) . This was accomplished by constructing levees and wing dams to direct the river 's flow into a straight , narrow channel and prevent sedimentation . In 1925 , the USACE began a project to widen the river 's navigation channel to 200 feet ( 61 m ) ; two years later , they began dredging a deep @-@ water channel from Kansas City to Sioux City . These modifications have reduced the river 's length from some 2 @,@ 540 miles ( 4 @,@ 090 km ) in the late 19th century to 2 @,@ 341 miles ( 3 @,@ 767 km ) in the present day . 
