Renters treat "on the Green Line" as a single attribute, the way you'd treat being on the Red Line. It isn't. The Green Line has four branches, they run on genuinely different kinds of track, and the difference shows up in your commute every day.
A shorter line on the map doesn't mean a shorter ride. Two apartments equidistant from downtown can have very different commutes depending on which branch actually serves them.
The four branches, and what actually separates them
| Branch | Runs to | Through | Track type | What that means day to day |
|---|---|---|---|---|
| B | Boston College | Commonwealth Avenue, through Allston/Brighton and BU | Median reservation on a busy surface street | Frequent stops and traffic signals. The slowest of the western branches |
| C | Cleveland Circle | Beacon Street, through Brookline | Median reservation on a surface street | Surface running with regular stops, but a shorter run than the B |
| D | Riverside and Union Square | Brookline Village, Newton, and now Somerville | Largely its own grade-separated right-of-way | Traffic barely touches it. The fastest of the branches |
| E | Heath Street and Medford/Tufts | Huntington Avenue, Longwood, Mission Hill | Reservation, then mixed traffic on the outer section | The outer end shares road space with cars |
All four converge downtown through the Tremont Street subway, the oldest subway tunnel in North America. Once you're underground, you're on the same line as everyone else. The differences are all above ground.
Why track type is the whole explanation
Track type determines each branch's speed, not distance from downtown.
The D branch runs on a former railroad alignment. It has its own grade-separated right-of-way for most of its length, which means no traffic lights, no cars, no left-turning vehicles blocking the tracks. That's why it moves well even though it runs further out than the others. Riverside is considerably further from downtown than Boston College, but the trip doesn't feel proportionally longer.
The B and C branches run in median reservations. They have their own strip down the middle of Commonwealth Avenue and Beacon Street respectively, but they cross traffic at intersections, they stop frequently, and they're subject to everything happening on a busy road. The B branch has more street-level stops than any other branch and carries heavy university traffic through the BU stretch, which is the usual explanation for its reputation.
The E branch's outer section runs in mixed traffic. Beyond a certain point on Huntington Avenue the streetcars share road space with cars outright, which is a different experience again.
The ranking commonly cited for the branches, D fastest and B slowest, isn't an opinion about service quality. It follows from what each branch is physically running on. We haven't put minute figures on any of it, because those vary by time of day and we'd rather give you the mechanism than a number that's wrong at rush hour.
Which branch serves where you're looking
| If you're looking in… | Branch | Our guide |
|---|---|---|
| Allston / Brighton | B | — |
| Brookline | C and D (B just outside town) | Living in Brookline |
| Newton | D (seven stops) | Living in Newton |
| Somerville | D, via the Extension | Renting in Somerville |
| Cambridge | D at the eastern edge; the Red Line does most of the work | Living in Cambridge |
| Longwood / Mission Hill | E | — |
| Cleveland Circle | C, with B and D nearby | — |
Note the Brookline row. Two branches run through Brookline, the C and the D, and the B runs just outside it, which means "it's in Brookline" tells you almost nothing about the commute. A Beacon Street apartment on the C and a Brookline Village apartment on the D are different propositions, and the town name doesn't distinguish them. If you're looking there, identify the branch before the neighborhood.
What the Green Line Extension changed
The Extension added stations that weren't there before, so if you're reading older advice about the Green Line, some of it predates the change.
The Extension pushed the D branch out to Union Square and the E branch north to Medford/Tufts. Somerville, which had no Green Line station at all before, now has several, and the map that most guides describe is out of date.
That matters for anyone comparing Somerville to Brookline or Newton on transit. The comparison changed. Our guide to living near the Green Line Extension covers which Somerville neighborhoods actually gained a station and what it did to them.
How to actually choose
Work backwards from where you're going, not forwards from the neighborhood.
Start with your destination. If you work downtown, any branch gets you there and the question is how long the surface section takes. If you work at Longwood, the E is a direct ride and the others involve a change. If you work in Kendall or Harvard, the Red Line probably matters more than any of this.
Then check the walk to the stop. Branch quality matters less than a fifteen-minute walk at both ends. Two apartments on the same branch can differ substantially just on how far you are from the platform.
Then check whether you'd need to change. Being on a branch that reaches your destination without a downtown transfer is worth more than being on a nominally faster branch that doesn't.
This is easier to do at the search stage than after. Spot Easy lists Boston-area apartments by transit proximity, so you can filter for the line and stop you'd actually use rather than working it out listing by listing.
One more thing if you drive as well: the branch tells you nothing about parking, and the rules vary sharply by municipality. Brookline in particular bans overnight street parking, which catches people who chose the neighborhood on transit alone.
Frequently asked questions
Are the Green Line branches actually different? Yes. They run on different kinds of track — the D on its own grade-separated right-of-way, the B and C in street medians, the E partly in mixed traffic — which is why they behave differently.
Which Green Line branch is fastest? The D, because most of it runs on a former railroad alignment away from traffic.
Why is the B line slow? It runs in the median of Commonwealth Avenue with more street-level stops than any other branch, crossing traffic at intersections, through a heavily used university stretch.
Which branch goes to Longwood Medical Area? The E, along Huntington Avenue.
Which branches serve Brookline? The C and the D run through Brookline, and the B runs just outside it along Commonwealth Avenue in Boston, within walking distance of North Brookline. The town name alone doesn't tell you much about a commute.
Did the Green Line Extension change things? Yes. The D now runs to Union Square and the E to Medford/Tufts, giving Somerville several stations it didn't have before.
Do all branches go downtown? Yes, all four run through the Tremont Street subway once they're underground.
Should I pick a neighborhood based on the branch? Pick it based on your destination and your walk to the stop. The branch matters, but a long walk at either end usually matters more.
Sources
Branch termini, routing and track types are as documented by the MBTA and its branch references, checked August 2026: the B branch along the Commonwealth Avenue median from Boston College, entirely within Boston city limits; the C branch from Cleveland Circle along the Beacon Street median through Brookline; the D branch serving Boston, Brookline, Cambridge, Newton and Somerville between Riverside and Union Square; and the E branch between Heath Street and Medford/Tufts.
The comparison of how the branches behave follows from those track types rather than from a published ranking. We have deliberately published no journey times, headways or frequencies, because they vary by time of day and we have not verified a current set.
Service patterns change. Check the MBTA for current service before planning around any of this.