The Providence/Stoughton Line is the busiest, longest and only interstate MBTA Commuter Rail Line. The core of the line operates on the most northern 63 miles of the Northeast Corridor from Boston-South Station to Wickford Junction, Rhode Island. There is also a short 4.1 mile branch to Stoughton that branches off the mainline at Canton Junction. This line may be eventually electrified and extended to provide service (on a more direct route than phase 1 via the Middleborough/Lakeville Line) to Fall River and New Bedford under Phase II of the South Coast Rail Project.

Today service on the core of the line between Providence and Boston-South Station is roughly hourly (not clockface schedules) on weekdays with more frequent rush hour service, and roughly every two hours on weekends.

Service to TF Green and Wickford Junction operates via 8 trains that are extended south on Weekdays only, largely during rush hours and middays(in both directions), there is no evening service as of the May 2023 schedule changed (this required your webmaster to rethink a round-trip I was doing on MBTA Commuter Rail on Juneteenth while staying at the Hyatt Place at the TF Green Airport station). Service on the Stoughton Branch is roughly hourly on weekdays only (there is a two hour gap in the middle of the day). There is no weekend service south of Providence or on the Stoughton Branch.

The portion of the line in Rhode Island is operated under contract with the Rhode Island Department of Transportation. The line was previously called the Attleboro/Stoughton Line during years when there was no service into Rhode Island at all (such as from February 20, 1981 until February 5, 1988) or service to Providence was during Peak Hours only. Some off-peak service to providence began in 2000 with Weekend service beginning for the first time in 2006. Commuter Rail Service south of Providence didn’t begin until 2010 when limited service was extended to TF Green Airport, and later Wickford Junction in 2012.

The mainline (except for the branch to Stoughton) was electrified by Amtrak under the Northeast High Speed Rail Improvement Program as part of the implementation of the Acela Express that was completed in 2000. This electrification didn’t include the two platforming tracks at Attleboro along with the single siding tracks and platforms that that new TF Green Airport and Wickford Junction Stations were built upon 20 years later.

The situation at these stations, plus the MBTA not wanting to purchase special electric locomotives or EMU trainsets exclusively for the Providence Line means that all trains continue to operate with diesel locomotives under wire.