From Ancestry.com Wiki
Southbridge is a town in Massachusetts. It was formed in 1816 and was previously called Charlton/Dudley/Sturbridge. It can be found in Worcester county and is a part of the Worcester registry of deed district. For more information, contact the county at 41 Elm St., Southbridge 01550. On the attached map, Southbridge is shown as 54 in Worcester county.
For information about the state of Massachusetts see Massachusetts Family History Research.