Polk County is a county located in the U.S. state of North Carolina. As of the 2020 census, the population was 19,328. Its county seat is Columbus. The county was formed in 1855 from parts of Henderson and Rutherford counties. It was named for William Polk, a colonel in the American Revolutionary War. The Tryon International Equestrian Center, close …Polk County is a county located in the U.S. state of North Carolina. As of the 2020 census, the population was 19,328. Its county seat is Columbus. The county was formed in 1855 from parts of Henderson and Rutherford counties. It was named for William Polk, a colonel in the American Revolutionary War. The Tryon International Equestrian Center, close to the community of Mill Spring was the location of the 2018 FEI World Equestrian Games.