6624
This contributed to the economic development of the Southern United States , a prime cotton growing area ; some historians believe that this invention allowed for the African slavery system in the Southern United States to become more sustainable at a critical point in its development .
 location: Southern United States; location: Southern United States
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: Southern United States, Southern United States 
Answer:
 location: Southern United States; location: Southern United States