According to Rural Policy Matters for November, 2009 the five states with the highest percentage of students enrolled in rural school districts are:
Maine 54%
Vermont 53%
South Dakota 51.3%
North Carolina 47.8%
Mississippi 47.1%
Alabama is a close 6th with 41.4%
I would not have picked all of them. It is interesting that North Carolina, Mississippi and Alabama are among the states with the highest number of students who do not complete high school. Is there a correlation?