 In the late 19th and early 20th centuries , a great number of dams were built along the course of the Missouri , transforming 35 percent of the river into a chain of reservoirs . River development was stimulated by a variety of factors , first by growing demand for electricity in the rural northwestern parts of the basin , and also by floods and droughts that plagued rapidly growing agricultural and urban areas along the lower Missouri River . Small , privately owned hydroelectric projects have existed since the 1890s , but the large flood @-@ control and storage dams that characterize the middle reaches of the river today were not constructed until the 1950s . 
 In the late 19th and early 20th centuries , a great number of dams <a href='uninflect' title='1'><mark>were</mark></a> built along the course of the Missouri , transforming 35 percent of the river into a chain of reservoirs . River development was stimulated by a variety of factors , first by growing demand for electricity in the rural northwestern parts of the basin , and also by floods and droughts <a href='null_relcl' title='2'><mark>that</mark></a>plagued rapidly growing agricultural and urban areas along the lower Missouri River . Small , privately owned hydroelectric projects <a href='been_done' title='3'><mark>have</mark></a> existed since the 1890s , but the large flood @-@ control and storage dams <a href='null_relcl' title='4'><mark>that</mark></a>characterize the middle reaches of the river today <a href='uninflect' title='5'><mark>were</mark></a> not constructed until <a href='None' title='6'><mark>the</mark></a><a href='negative_concord' title='7'><mark>1950s</mark></a> . 
In the late 19th and early 20th centuries , a great number of dams was built along da course of the Missouri , transforming 35 percent of the river into a chain of reservoirs . River development was stimulated by a variety of factors , first by growing demand fa electricity in the rural northwestern parts of the basin , and also by floods and droughts plagued rapidly growing agricultural and urban areas along tdalower Missouri River . Small , privately owned hydroelectric projects done existed since the 1890s , but thdaigass flood @-@ control and storage dams characterize thedaddle reaches of the river today was not constructed until no 1950s .