A question: why is New Hampshire so conservative, relative to its neighbours?

New Hampshire was the only state in new england Bush won in 2000. As of the time of writing, Kerry enjoys huge leads in each of New Hampshire's neighbours: 10% in Maine, 24% in Massachusetts, 15% in Vermont. Kerry also has sizeable leads in the rest of new england, with 24% in Rhode Island and 10% in Connecticut. However, Bush and Kerry are tied in New Hampshire.

Why is this state so much more conservative than the rest of new england?