What county in the 10-county Atlanta Regional Commission had a population of 259,424 during the 2010 census?
Atlanta Regional Commission: The Atlanta Regional Commission (ARC) is the regional planning and intergovernmental coordination agency for the metro Atlanta, Georgia, USA region, defined as the 10-county area of Cherokee, Clayton, Cobb, DeKalb, Douglas, Fayette, Fulton, Gwinnett, Henry and Rockdale counties, including the city of Atlanta.
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