A hundred years ago New England was progressive, true, but it was also a center of business especially manufacturing interests and socially conservative in the sense of wanting public morality ie banning prostitution and abortion which was as an aside an important tenent of Progressivism. When and why did the Boston Brahmins, Boston Irish, and rustic Vermont farmers all become so liberal?
I assume you are talking about social liberalism versus economic liberalism. I am a native born Southerner but I have lived in Vermont, Boston proper, and now in the outer Boston suburbs. The groups you name are all very different.
Vermont is very rural. It is one of the most least populated states and many parts of it are throwbacks to centuries past. They still have honest-to-god general stores with three movies to rent, one rifle for sale, and four pairs of snow boots in assorted sizes. They can also make you a sandwich behind the counter if you ask. It can mostly be described as libertarian (New Hampshire even more so) but lots of wealthy Bostonians and New Yorkers have vacation houses in Vermont and that certainly has an impact. Neighboring New Hampshire could easily be a Southern state if you just hired a tug-boat and pulled it down South and gave the population speech lessons. It isn’t liberal at all except for the extreme southern part which are the distant Boston suburbs.
One theory I have about Northern New England is that no one has to be worried about minorities, inner city crime, or true poverty. It exists in isolated pockets but New Hampshire, Maine, and Vermont are among the whitest states in the U.S. and fairly wealthy. If it wasn’t so damned cold 6 months of the year, those states would be about the most perfect places on earth. They play arm-chair quarterback for the rest of the nation because they simply can’t comprehend any problems that are going on anywhere else in the country.
There aren’t very many Boston Brahmins around anymore but the stereotypical ones are very wealthy and they can easily pay lip service to being socially liberal because they have the means to hold things like charity events. There is nothing wrong with that but it does become part of their image. Wealth gives you freedom to build whatever image you want people to see.
The general class of the Boston Irish aren’t known for being progressive at all. In fact, they are known for being quite racist to this day. One of the biggest racial scandals in the U.S. was the “school busing” controversy of the 1970’s in which poor black kids were bused to new schools to get a better education and the clash between those groups was heated and severe and is now part of American history on what not to do.
The basic answer for why Boston is so liberal is that it is education central for the world. Harvard and MIT are right down the street from one another in Cambridge and they attract some of the smartest people around but they are Ivory Tower types. There are over 100 colleges and universities in the greater Boston area the last time I checked so students and faculty are always flooding in.
I am fairly socially liberal myself and I was once in Ivy League academia but I fully admit those fields attract some odd types. With so many of them around this area, it does make an impact.
I agree with most of what Shagnasty says. Another factor is the types of religions in NE. They tend to be the old-school ones where there isn’t a lot of witnessing. You go to church on Sunday then don’t talk about it much in between. This includes Episcopals, Unitarians, and also Catholics. They also have a lot of Jewish people so it would be rude to go around saying how it’s a Christian country. Jewish people also tend to be more liberal.
It may be more accurate to ask why the rest of the country is so conservative. Boston is more like the rest of the world. It has the feel of a European city and has similar values. When New Englanders see the Palins and Joe the Plumbers and Evangelists they just don’t seem like their kind of people.
I’d say that rural new England is pretty much the same as it was a few hundred years ago because it grew up before cars. Small towns, small farms, cute little churches. In much of the rest of the country it’s been build for cars: malls, mega churches, no place to walk and get groceries.
No kidding? I’m sure that would come as quite a surprise to the billions of people who live in South and Central America, the Carribean, Africa, the Middle East, Russia, China, the Far East, The Pacific Ilands, etc., etc., etc.?
And besides, who died and made Europe the ideal of human progress? Europe is crowded, bogged down in beaurocracy and red tape, full of crooks and tourist traps and pickpockets, has triggered two world wars, and everybody smokes. Plus they drive dinky little cars (if they even have cars, that is) and everybody lives in dinky little houses and apartments. And they have royalty. And aristocrats. And there are still some private companies and people there who actually make their own money. Why, some parts of it actually cater to people with money.
So, how is it that Boston is like the rest of the world again? 
Boston used to be the center of anti-Semitism in America. Harvard imposed a quota on Jewish students after enrollment hit 20% in 1920. A Different Mirror: A History of Multicultural America by Ronald Takaki quotes a number of statements by Harvard’s President, Abbott Lawrence Lowell, as patrician a name as ever reigned, about how Jews were taking over wherever they were let in. He wanted to cut their numbers by at least a quarter. Of course, he justified his statements by saying how prevalent anti-Semitism was among students and alumni so he was suggesting it to protect the Jewish students. Sure.
New England’s liberalism doesn’t really date back before WWII and much of it is quite recent. Boston politics was traditionally Democrat due to its political machine dominated by Irish Catholics who as noted were virulently bigoted. Boston sports teams were among the last to fully integrate and their athletes complained that they weren’t accepted for the whole of the 20th century.
Liberalism is highly correlated with urbanism. Even in the South, urban areas tend to be much more liberal than rural areas. New England is almost entirely urbanized today, one continuous mass of cities and suburbs that extend forever. The reasons why rural areas are so much more conservative have been explored by many authors, but in general proximity breeds acceptance over time. That’s been cities’ historic experience and it’s now working in suburbs as well as they become denser and more multicultural.
Those of us born in California are frequently semi-uninformed about the Eastern Seaboard with respect to politics, social conditions, etc.
Thank you for those very erudite responses, Shagnasty and Exapno Mapcase.
That is all.
However weren’t many New Englanders strict Congregationalist Calvinists who were the ideological descendents of the Puritans at least before World War 2? Also a lot of Catholics are social conservatives. As for the Boston Irish being rather racist and old-fashioned then why are most Irish American politicians especially the Kennedys so liberal?
Which American city are these places more like then?
The Kennedys are a name brand like Coca-Cola. The last significant one (Ted Kennedy) died not very long ago. They don’t represent the typical Irish-Americans in Southie. They always had their own thing going on. I fully admit that I have never understood Massachusetts politics. It has produced some of the best Republican governors in the U.S. William Weld was one but Mitt Romney was pretty talented as well and both are conservatives. You would have to move to the Boston area to understand it and, even then, you would be doing better than I ever will if you do.
I dunno, Birmingham, Alabama or Jacksonville, Florida.
I’m assuming this is tongue-in-cheek. If not, well it is a model of progress in many ways. Where else do you have numerous small countries, each of which has retained its own distinctive culture and usually its own language and vast amount of physical history? And where there are not vast differences in average living standards between one country and another, so citizens of one die trying to cross a burning desert to reach the other? We could learn something here…
All politics is local said Tip O’Neill, D-MA.
The 20th century is full of examples of working class Democrats fighting for labor rights and social reforms while loudly denouncing segregation, immigration, and acculturation. People and parties aren’t monolithic.
“Liberal” Republicanism was a force pretty much limited to the northeast for its entire existence. Maine’s two Republican Senators are probably the most moderate Republicans in the Senate. I can’t speak of Representatives because there aren’t any. Every seat in the House east of the Hudson River is Democratic.
And although I’m watching from afar weren’t both Weld and Romney considered to be on the far moderate wing of the party while in office? Jesse Helms wouldn’t allow Weld to become an Ambassador (under Clinton!) because he was too liberal. Romney was never considered sufficiently conservative even after he repudiated every earlier stance in the last presidential election cycle. New England Republicans can be only so conservative and survive, while in other parts of the country there is no limit to the depths of conservatism that is approved.
That’s an oversimplification. The Republicans and Democrats have basically traded positions over the last 50 years. One could argue that Republicans were the historically more liberal party as they advocated a stronger central government and were the party of Lincoln. There used to be lots of Republicans in office in New England until the Southern Strategy alienated them. The idea that Democrats are liberal and Republicans are conservative is a recent phenomenon.
Actually Republicans for a rather long time have advocated smaller government. For instance compare McKinley and Taft to William Jennings Bryan or Calvin Coolidge to FDR.
If you had an Irish name you already appalled to the Irish base, so the rest of your positions were to attract everyone else. 
Religion in New England is different than it is in the South. It’s pretty much a private thing. Maybe it’s because there is so much diversity. At any large gathering you’ll have at least one Jewish person, Catholic, and Protestant. You would rarely hear something like “he jewed me down” because it’d likely offend someone. People also identify more with a specific religion. You’d say you are a Lutheran, or Episcopalian, or Methodist rather than a “Christian”.
You also don’t have the cult of Jesus with people talking about having a personal relationship with him, or addressing him in a public prayer.
And many Democrats have long called for a smaller government as well. Look at all the “states rights” rhetoric from the solid Democratic south.
Putting aside the parties, the North (which used to mean north east) has always wanted a stronger (not necessarily bigger) government than the south. This may be because they had bigger interest in trade and banking than the more agricultural south.
Already pre-WW2 the process of mergers had begun that led those churches to now be part of the United Church of Christ, usually considered a liberal affiliation.
And I must agree from my experience working with people from the region that Upper New England is quite its own world as opposed to points south of the Mass. border. (I’ve mentioned in other threads that I know and have worked in the past with Vermont Governor Douglas, one of the Last Republicans Standing in NE. Quite a fine example of a sane conservative, back when he was State Treasurer he once got nominated by BOTH parties. I wonder how would that play in Boston.) I do feel like there’s some validity in what was mentioned, that a lack of easily definable Us-vs-Them lines until very recently meant the more antagonic version of conservatism dominating the GOP post-Nixon lost traction (and never mind the faction wanting to turn it into the Jesus Party).
This is a pretty good overview, especially wrt the northern new england states (who are as much libertarian than anything else).
But I would also content that New England has pretty much always been liberal by the standards of the day. For example, compulsory public education and the Abolitionist movement, both in the first half of the 1800’s, largely got their start in New England.
Groups of people are not the same thing as regions. Just because small groups can advocate things that later became widespread doesn’t mean they were widespread at the time.
And it’s hard to push today’s connotations of liberal and conservative into the 19th century. Abolitionists also tended to believe in other isms like prohibition. Is that liberal or conservative thinking? Were the Transcendentalists profoundly liberal or profoundly conservative?
And if you’re going to cite liberal movements, why not note the region’s puritan heritage and behavior? Banned in Boston was once a catch phrase because censorship of books and entertainment was noted there.
I’d keep the 19th century out of this discussion. It doesn’t play by our rules.
You mean southern New England. Northern New England and parts of western Mass. are mostly rural and semi-rural.