 The table on the right lists the ten longest tributaries of the Missouri , along with their respective catchment areas and flows . Length is measured to the hydrologic source , regardless of naming convention . The main stem of the Kansas River , for example , is 148 miles ( 238 km ) long . However , including the longest headwaters tributaries , the 453 @-@ mile ( 729 km ) Republican River and the 156 @-@ mile ( 251 km ) Arikaree River , brings the total length to 749 miles ( 1 @,@ 205 km ) . Similar naming issues are encountered with the Platte River , whose longest tributary , the North Platte River , is more than twice as long as its mainstream . 
 The table on the right <a href='uninflect' title='1'><mark>lists</mark></a> the ten longest tributaries of the Missouri , along with their respective catchment areas and flows . Length is measured to the hydrologic source , regardless of naming convention . The main stem of the Kansas River , for example , <a href='drop_aux' title='2'><mark>is</mark></a>148 miles ( 238 km ) long . However , including the longest headwaters tributaries , the 453 @-@ mile ( 729 km ) Republican River and the 156 @-@ mile ( 251 km ) Arikaree River , <a href='uninflect' title='3'><mark>brings</mark></a> the total length to 749 miles ( 1 @,@ 205 km ) . Similar naming issues are encountered with the Platte River , whose longest tributary , the North Platte River , <a href='drop_aux' title='4'><mark>is</mark></a>more than twice as long as its mainstream . 
The table on da right list the ten longest tributaries of the Missouri , along witt their respective catchment areas and flows . Length is measured to tdahydrologic source , regardless of naming convention . The main stem of the Kansas River , fir example , 148 miles ( 238 km ) long . However , including thdaongest headwaters tributaries , the 453 @-@ mile ( 729 km ) Republican River and theda6 @-@ mile ( 251 km ) Arikaree River , bring the total length to 749 miles ( 1 @,@ 205 km ) . Similar naming issues are encountered with the Platte River , whose longest tributary , the dath Platte River , more den twice as long as its mainstream .