 That is a 7% increase over last year. Passenger activity is forecasted to remain high through Labor Day with a continued 13% increase in passengers over last year. Charleston has reclaimed the title of South Carolina's largest city from Columbia going back to 2017. It was a close call between population and area size. Experts telling the Post and Courier, city populations can be complex due to varying methods. One example is city limits may not accurately reflect urban areas.