Probably by what kind of current they get there.
North/South Dakota North/South Carolina
There are 5 US states that have "directions" (north, south, east, or west) in their names : North Carolina, South Carolina, North Dakota, South Dakota, and West Virginia.
North Dakota South Dakota North Carolina South Carolina
North Korea and South Korea
north and south actually Santa lives in the north
North Carolina, South Carolina, North Dakota, and South Dakota.
North Dekota, South Dakota, North Carolina and South Carolina
Panama separates the North from the South
It should be rather obvious that South Carolina is the one to the south and North Carolina is the one to the north. That's why they were named those names.
They are proper names of direction.
North Carolina and South Carolina
North Carolina and South Carolina