river rising in south central Worcester County, Mass., U.S., and flowing generally southeast past Worcester city and Northbridge, Mass.; it continues across the northeast corner of Rhode Island, past Woonsocket, Central Falls, and Pawtucket, where it becomes the Seekonk River (q.v.). In its course of about 50 mi (80 km), the Blackstone furnishes power to a highly industrialized region. It was named for William Blackstone, first white settler in what is now Cumberland, R.I.