- Southern Terminus:
- Rhode Island-Massachusetts state line
- Northern Terminus:
- Blue Hills Parkway (MA 28) in Milton
- 43.68 miles
- Bristol, Norfolk
MA 138 is a continuation of RI 138 into Massachusetts. RI 138 turns into MA 138 at the state line, and it runs north through Fall River along South Main Street and Broadway. After passing under the Braga Bridge, where I-195 crosses the Taunton River, Broadway becomes Davol Street, the service roads of the Western Fall River Expressway (MA 79). US 6 joins MA 138 for the northernmost few blocks of Davol Street. Then, both routes turn west and cross the Taunton River. On the other side, MA 138 splits off and runs north to Taunton. It continues north to Milton, where it merges into MA 28 and ends.