Millbury is a town in Worcester County, Massachusetts, United States. Located within Blackstone Valley, the population in Millbury was 13,831 at the 2020 United States census. Millbury was first settled by Europeans in 1716. It was originally known as the Second or North Parish of Sutton. Because traveling from one part of the town to the other for meeting…Millbury is a town in Worcester County, Massachusetts, United States. Located within Blackstone Valley, the population in Millbury was 13,831 at the 2020 United States census. Millbury was first settled by Europeans in 1716. It was originally known as the Second or North Parish of Sutton. Because traveling from one part of the town to the other for meetings was time-consuming, inhabitants of the North Parish petitioned the Massachusetts General Court to split Sutton. North Parish became Millbury on June 11, 1813, by way of an act of incorporation. Its name derived from its long history as a mill town. The Blackstone River flows through the town, and during the Industrial Revolution, provided water power to its many textile mills and factories. During this time, the inventor William Crompton worked in Millbury.