6001
In 1809 , the last major river pirate activity , on the Upper Mississippi River , came to an abrupt end , when a group of flatboatmen , meeting at the head of the Nine Mile Reach , decided to make a raid on Stack Island and wipe out the river pirates .
 Mississippi
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Mississippi