what countries does the mississippi river run through?
United States of America
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 A river of sea water , called the Atlantic North Equatorial Current , flows westward off the coast of Central Africa . When this current interacts with the northeastern coast of South America , the current forks into two branches . One passes into the Caribbean Sea , while a second , the Antilles Current , flows north and east of the West Indies . These two branches rejoin north of the Straits of Florida . 

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 The river flows through several areas of ecological interest and supports a variety of rare and endangered species . 

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 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 straightened 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 . 

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 The Missouri River is the longest river in North America . Rising in the Rocky Mountains of western Montana , the Missouri flows east and south for 2 @,@ 341 miles ( 3 @,@ 767 km ) before entering the Mississippi River north of St. Louis , Missouri . The river takes drainage from a sparsely populated , semi @-@ arid watershed of more than half a million square miles ( 1 @,@ 300 @,@ 000 km2 ) , which includes parts of ten U.S. states and two Canadian provinces . When combined with the lower Mississippi River , it forms the world 's fourth longest river system . 

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 In 1929 , the Missouri River Navigation Commission estimated the total amount of goods shipped on the river annually at 15 million tons ( 13 @.@ 6 million metric tons ) , providing widespread consensus for the creation of a navigation channel . However , shipping traffic has since been far lower than expected – shipments of commodities including produce , manufactured items , lumber , and oil averaged only 683 @,@ 000 tons ( 616 @,@ 000 t ) per year from 1994 to 2006 . 
