Columbia County is a county in the Commonwealth of Pennsylvania. It is located in Northeastern Pennsylvania. As of the 2020 census, the population was 64,727. Its county seat is Bloomsburg. The county was created on March 22, 1813, from part of Northumberland County. It was named Columbia, alluding to the United States and Christopher Columbus. Columbia County is part of the Bloomsburg-Berwick, PA Metropolitan Statistical Area.