63279
A series of 29 locks and dams on the upper Mississippi , most of which were built in the 1930 s , is designed primarily to maintain a channel for commercial barge traffic .
 location: Mississippi
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Mississippi 
Answer:
 location: Mississippi