A remarkable thing happened last Tuesday. The Republican Party was virtually extinguished from the land of its birth.

I’m speaking of Yankeedom, a great swath of the country from Maine to Minnesota that was effectively colonized by New England Puritans and their descendants. This cultural region – one of eleven that make up our continent — includes upstate New York, the Western Reserve of Ohio, Upper Great Lakes states, the northern tier of Illinois, and part of Iowa. The birthplace of the G.O.P and the center of its support for the first century of its existence, today it is home to 54 million people, few of them genetically related to the early settlers of the Bay Colony, but all of them effected by the cultural DNA they left behind.

It’s a region that since its founding in the early 17th century has embraced the notion of the common good, even to the point of encumbering individual liberty to ensure its achievement. It’s a culture that actually considers self-denial virtuous (how strangely un-American that) and has greater faith in the possibility of improving society through public institutions than its peers. More utopian and communitarian than the other major cultural regions of the country, it has long been a challenge for Dixie conservatives seeking to weaken government, privatize services, and roll back taxes, regulations, and consumer safety protections.

A year ago in the magazine, I showed how the underlying political geography of the U.S. would doom Tea Party conservatism to regional, rather than national, relevance. The policy prescriptions embraced by the movement – a carbon copy of those said Dixie conservatives have been fighting for for a couple of centuries – run contrary to the values of Yankeedom and other regional cultures which together form a formidable block in the Electoral College, U.S. Senate, and Congress. I showed how the Tea Party had had difficulty electing its supporters to federal office in these regions, and how those they had were standing on cultural quicksand.

Tuesday in Yankeedom, most of them fell through, dragging fellow Republicans into the deep on their coat tails.

It was a regional rout of national significance. In New England, Mitt Romney didn’t capture a single Electoral College vote, while Republicans lost every major federal and statewide contest. Scott Brown lost his U.S. Senate seat to Democrat Elizabeth Warren in Massachusetts. In Maine, two-term Independent Gov. Angus King routed his rivals to capture the U.S. Senate seat being vacated by moderate Republican Olympia Snowe, while Republicans lost control of both houses of the state legislature. In “Live Free or Die” New Hampshire, Republicans lost both U.S. House contests and – in a massive turnaround – the lower chamber of the State House; Democrat Maggie Hassan was elected governor.

New England now doesn’t have a single G.O.P. congressperson. Only one of its six governors and two of twelve U.S. Senators are Republicans.

And it’s not just in the New England core. Romney lost every state dominated by Yankeedom – Michigan, Wisconsin, Illinois, and Minnesota – and all those with significant Yankee sections, including New York and Ohio. Republican U.S. Senate candidates lost in every Yankee dominated state as well, while Democrat Sherrod Brown owed his Senate victory in Ohio to overwhelming support in the Yankee-founded Western Reserve. Republicans lost 10 of 12 Yankee-controlled House seats in Illinois, 5 of 8 in Minnesota, 4 of 9 in upstate New York, and both in eastern Iowa. They clearly lost the Western Reserve as well, though intense gerrymandering of that Democratic bastion makes a firm count of districts impossible. Only in Michigan and Wisconsin will the G.O.P. house caucus represent a majority.

Back when the national party stood for fiscal responsibility, social progress, and the protection of the environment, Republicans dominated this region. So long as it embraces the Tea Party agenda, expect it to remain a critically endangered species in its native habitat.