Fulton County is a county in the north central portion of the U.S. state of Georgia. As of 2015 estimates, the population was 1,010,562, making it Georgia's most populous county and the only county with over 1 million inhabitants. Its county seat is Atlanta, the state capital since 1868. Ninety percent of the City of Atlanta is within Fulton County. Fulton County is the principal county of the Atlanta metropolitan area.