Did the moderate WASP Republican brigade decide to show up in full force that day?
Was there something about Carter that Massachussites just didn't like?
Did Carter's "Born Again" image rub off the wrong way on Massachusetts liberal intellectuals?
Did Catholics feel put off by a Baptist running for President?
1.) Not Sure
2.) Lower 2
3 and 4.) Probably, judging by the swing against Carter in North and South Boston.
Here's the 1972-1976 swing by congressional district. Sorry I don't have the regular county map, but this will work.