To wrap up what we've seen so far: although New Hampshire remained a solidly Republican state in presidential elections through the 1980s, significant changes were underway at the county level.  During the 1960s, five counties voted at least 5 points more Republican than the entire state.  By the 1980s, that number had dropped to just two, Belknap and Carroll - and both were losing their GOP tilt.

Was the state's population growth the main reason for the shift in its politics?  Results are mixed: remember, the two largest counties, Rockingham and Hillsborough, wind up moving in different directions politically during the 1960s and ‘70s.

Another possible culprit: changes in the national Republican Party itself.  To put it another way: was Ronald Reagan good for the New Hampshire GOP?  More next time.