The Terryville Union Hall was built circa 1887 with land and materials donated by Thomas R. Terry to the Terryville Union Society. This society was an early version of a civic association. The Hall was built to serve as a place for a coming together or a union of the people of Terryville or Cumsewogue, (the native American name for the area) as it was originally called. It also served as a Grange Hall as well as a non-denominational Sunday School.
The Union Hall was declared a Brookhaven Town Landmark and chartered by the State of New York in 2009.