Milford to W. Roxbury
The original 109 went from Pittsfield to West Brookfield along what is now MA 9. This number was removed by 1933.
The modern 109 was posted by 1933; presumably when the old one was taken down. It remains basically the same. The route now ends at VFW Parkway, former US 1. As this is now unnumbered, MA 109 just ends at an unnumbered street. MA 203 and MA 228 also do this.