 By tonnage of transported material , Missouri is by far the largest user of the river accounting for 83 percent of river traffic , while Kansas has 12 percent , Nebraska three percent and Iowa two percent . Almost all of the barge traffic on the Missouri River ships sand and gravel dredged from the lower 500 miles ( 800 km ) of the river ; the remaining portion of the shipping channel now sees little to no use by commercial vessels . 
