 In 1682 , France expanded its territorial claims in North America to include land on the western side of the Mississippi River , which included the lower portion of the Missouri . However , the Missouri itself remained formally unexplored until Étienne de Veniard , Sieur de Bourgmont commanded an expedition in 1714 that reached at least as far as the mouth of the Platte River . It is unclear exactly how far Bourgmont traveled beyond there ; he described the blond @-@ haired Mandans in his journals , so it is likely he reached as far as their villages in present @-@ day North Dakota . Later that year , Bourgmont published The Route To Be Taken To Ascend The Missouri River , the first known document to use the name " Missouri River " ; many of the names he gave to tributaries , mostly for the native tribes that lived along them , are still in use today . The expedition 's discoveries eventually found their way to cartographer Guillaume Delisle , who used the information to create a map of the lower Missouri . In 1718 , Jean @-@ Baptiste Le Moyne , Sieur de Bienville requested that the French government bestow upon Bourgmont the Cross of St. Louis because of his " outstanding service to France " . 
 In 1682 , France expanded its territorial claims in North America to include land on the western side of the Mississippi River , which included the lower portion of the Missouri . However , the Missouri itself remained formally unexplored until Étienne de Veniard , Sieur de Bourgmont commanded an expedition in 1714 <a href='null_relcl' title='1'><mark>that</mark></a>reached at least as far as the mouth of the Platte River . It is unclear exactly how far Bourgmont traveled beyond there ; he described the blond @-@ haired Mandans in his journals , so it <a href='drop_aux' title='2'><mark>is</mark></a>likely he reached as far as their villages in present @-@ day North Dakota . Later that year , Bourgmont<a href='been_done' title='3'><mark></mark></a> published The Route To Be Taken To Ascend The Missouri River , the first known document to use the name " Missouri River " ; many of the names he gave to tributaries , mostly for the native tribes <a href='null_relcl' title='4'><mark>that</mark></a>lived along them , <a href='drop_aux' title='5'><mark>are</mark></a>still in use today . The expedition <a href='null_genetive' title='6'><mark>'s</mark></a>discoveries eventually found their way to cartographer Guillaume Delisle , <a href='null_relcl' title='7'><mark>who</mark></a>used the information to create a map of the lower Missouri . In 1718 , Jean @-@ Baptiste Le Moyne , Sieur de Bienville requested that the French government bestow upon Bourgmont the Cross of St. Louis because of his " outstanding service to France " . 
In 1682 , France expanded its territorial claims in North America to include land on the western side of the Mississippi River , which included the lower portion of da Missouri . However , the Missouri itself remained formally unexplored until Étienne de Veniard , Sieur de Bourgmont commanded an expedition in 1714 reached at least as far as the mouth of the Platte River . It is unclear exactly how far Bourgmont traveled beyond dere ; he described tdablond @-@ haired Mandans in his journals , soo it likely he reached as far as their villages in present @-@ day North Dakota . Later dat year , Bourgmont been published The Route To b Taken To Ascend Thdaissouri River , thedarst known document to use the name " Missouri River " ; many of the names he gave to tributaries , mostly fir the native tribes lived along them , still in use todayy . The expedition  discoveries eventually found their way to cartographer Guillaume Delisle , used the information to create a map of the lower Missouri . In 1718 , Jean @-@ Baptiste Le Moyne , Sieur de Bienville requested that the French government bestow upon Bourgmont the Cross of St. Louis because of his " outstanding service to France " .