The short (and incomplete) answer goes something like this:
The large majority of voters in Massachusetts live in "greater Boston"(this is is a very small state).Perhaps the most important "industries" of the Boston/Cambridge area are its hospitals and its large,"progressive" colleges (Harvard,MIT,Tufts,BU,BC,etc,etc).
*Many* of the people who live in "greater Boston" were educated at one of these schools and/or have some kind of current affiliation with them (faculty,administration,etc)
So if you come to understand how this nation's "progressive" colleges came under the control of leftists and that that control continues to this day,you'll understand why Massachusetts routinely elects swill like Kennedy,Kerry,Dukakis and the rest.
Thanks for explaining how higher education is a "big business" and political force in MA. I have met two persons from MA in the past decade: both were dismayed at the trends in their state. They feel politically isolated and unable to correct the problems there. MA has come a long way since the days of President Coolidge and even Senator JFK.