MA voters esp in Boston, Cambridge, Brookline, etc. voted Humphrey to counteract Nixon's southern strategy, at a time when textile jobs esp had moved south. This also explains Carter's poor showing in MA in '76. Humphrey also did better than Kennedy in VT and RI and especially in MA (with Muskie on the ticket).
It's great to see you bring back some of the old topics back for discussion.
Need to consider that Eisenhower won both in 1952 and 1956, and Nixon was effectively running for an Eisenhower third term, 60% was a good showing for Kennedy in his home state.
And New England became much more Democratic on a national level through the 1960s as the Eastern Republicans were losing steam to the conservative wing of the party. Nixon was running a more conservative campaign in 1968 than in 1960.