<P> The Corps of Discovery departed from Camp Dubois at 4 pm on May 14 , 1804 , and met up with Lewis in St. Charles , Missouri , a short time later , marking the beginning of the voyage to the Pacific coast . The Corps followed the Missouri River westward . Soon , they passed La Charrette , the last Euro - American settlement on the Missouri River . </P>
on which river did the exploration of the louisiana purchase begin
Missouri River