I view the particular station of "Harvard" more favorably than other squares, primarily because: It has two (very notable) interpretations, Harvard University and Harvard Square. Rather than picking one interpretation over the other, it actually feels nicer to have intentional ambiguity here -- as long as the shortened name, "Harvard", remains clear and sounds natural (which it is).
That's true, and like we discussed before, it's definitely a nice "feature" of "State" station, for example. "Prudential" is probably the strongest additional case of the "intentional ambiguity" scenario being effective.
Looking at the rest of your list (which, personally, I largely agree with, and also I agree illustrates the challenges with the principle), I'm struck by the number of them that could also be described using my "Small neighborhoods where the extent of the neighborhood matches the extent of the walkshed" approach. Ashmont and Kenmore, definitely, debatably Alewife, Maverick, Fairmount, and Assembly. Coming back to "Harvard", I think there's an argument to be made for the existence of a (micro)neighborhood called "Harvard", in which case it would fall into this category too.
Some comments on the ones that you would change (many of which I agree with)
This does not consider any "better names": only working based on current names.
- Butler -> Butler St
- Andrew -> Andrew Sq
- Kendall/MIT -> Kendall Sq/MIT
I think the inclusion of a second name after a slash is reason to drop "Sq" for concision. (I also think "Kendall" has the strongest argument of any Red Line North station to be referring to a neighborhood called "Kendall," and not just the square proper.)
- Central -> Central Sq Cambridge
- Porter -> Porter Sq
- There's a Porter Rd next to the station, but it's obviously much less notable
- Same for Porter St (Somerville) nearby, lol
- Davis -> Davis Sq
- Lechmere -> Lechmere Sq
- According to Wikipedia, the square got its name from "Lechmere's Point" on Revolutionary War maps; but apparently nobody is referencing "Lechmere's Point" today
- Boylston -> Boylston St
- Arlington -> Arlington St
- Copley -> Copley Sq
- Even though "Copley" as a station name is beautiful, AFAIK, there aren't any other locations known as Copley other than the square
- Especially as the City of Boston is calling the park "Copley Square Park" and not "Copley Park"
That's a really interesting note about the City calling it "Copley Square Park".
- Nubian -> Nubian Sq
- Looks like locals got the square renamed first, then pushed MBTA to rename the bus hub
- However, onboard bus announcements still say "Nubian Station", not "Nubian Square"
- Can "Nubian Station" itself be considered notable enough? I suppose not, especially due to:
- The young age of the "station"'s name (like Magoun Square)
- Before the rename, people also often referred to it as Dudley Square (rather than "Dudley Station"), even including the transit hub
- "Station" often implies a rapid transit station, and using that to call Nubian is blatant injustice
- Why the difference from Ruggles? It's a tough question, but:
- Ruggles's outreach is very broad by now due to its service coverage -- potentially someone from Providence can know to get off at Ruggles Station. But Nubian is generally known to a much smaller area.
- Nubian Square (and the previous name Dudley Square) are also more notable, and specific enough as a location indicator, than Ruggles St
Ruggles is probably exceeded only by Kenmore in terms of "stations named after minor streets where the station is now vastly more prominent than the street".
As for Nubian, I could be convinced either way (mostly by the community's perspective), but I think if we're going to add Sq to Davis, Porter, Central, Lechmere, Andrew, and Copley, then it's not a problem to just call it Nubian Square.
It sounds like
"Central Square Cambridge" is the shortest name that completely removes all ambiguities. That's admittedly too long, but:
- "Union Square Somerville" and "Union Square Allston" are equally long (and coincidentally in similar regions on the map as Central Square Cambridge), so their presence would make "Central Square Cambridge" less awkward
- As a by-product, it also naturally resolves any ambiguity with Central Square Lynn; even though (1) this isn't a big issue, and (2) any future rapid transit station at Central Square Lynn should simply be named "Lynn" anyway
Well, I guess I should have said in the first place that I don't love "Union Square Somerville" and "Union Square Allston" very much either

It's really a struggle though, because, like, those places
are both called "Union Square". The vague sense I get is that Somerville's has risen/is rising into being more of a neighborhood/microneighborhood, so perhaps it should get "dibs".
But Allston's also sits at, like, the worst intersection naming-wise:
- Cambridge St
- calling it "Cambridge St" would be confusing since it's not in Cambridge
- Brighton Ave
- calling it "Brighton Ave" would be confusing since it's not in Brighton
- North Beacon St
- nowhere near the normal Beacon St
- and North Beacon extends 2.5 miles west from here, so the "center of gravity" for that streetname is probably west of here also
Perhaps "Allston Union"?
Alternatively, perhaps something with the nearby Horace Mann School or the
Jackson/Mann Community Center?