The surprising, spectacular, and deeply encouraging failure of populism to move Democratic primary voters is only part of the story of the long overdue demise of the Clinton dynasty in North Carolina and Indiana Tuesday night. Just as decisive, if not moreso, was the near-total collapse of Hillary Clinton's support among African-Americans.

I'm not talking about the familiar collapse of Clinton's black support after Barack Obama proved himself to be a viable mainstream presidential candidate by winning the lily-white Iowa caucuses. A second mass exodus of black voters away from Hillary Clinton made Indiana a statistical push, fattened Obama's margins enough to completely wipe-out Clinton's pyrrhic, pointless victory in Pennsylvania, and broke down the wall of bullshit sustaining the idea that the Democratic primary didn't end in February.

After Obama's win in Iowa, her surrogates' public musings about Obama's possible history of crack dealing, and Bill Clinton's now infamous trashing of the Palmetto State as a consolation prize for the you-know-whats, Hillary Clinton still managed to pull in about one fifth of the black vote in South Carolina. Yet from one Carolina primary to the other, roughly two thirds of Clinton's remaining black support dissolved, only slightly less steep a drop, proportionally, than her fall from this October poll in which she actually led Obama in black support, to the South Carolina exit poll. If she had maintained her South Carolina performance among blacks on Super Tuesday, Potomac Tuesday, Super Tuesday II, and this past tuesday, the net shift would have been more than 500,000 popular votes --- enough to shrink Obama's popular vote lead to near parity, and perhaps take the lead on not terribly extravagant assumptions about non-black liberals who were turned off by the Clinton tactics.

The African-American Vote: Between the CarolinasThe handy chart to the right tells the story graphically. (I've explained my methodology below.) Clinton's share of the black vote declined by about one sixth between South Carolina and Super Tuesday --- a period when national polling showed Obama's support rising across all demographics, and Clinton's falling --- and declined a bit more than another fifth between Super Tuesday and the Potomac primaries at the peak of Obamamania, when (again) all his numbers were improving and hers were going in the other direction. When either economic and demographic factors or Plagiarismgate, Goolsbeegate, and various other pseudo-scandals broke Obama's winning streak in Ohio and Texas, Clinton's black support rose slightly (by about one sixth) --- just like her white and brown support.

Then the Wrightmare struck, a thousand innumerate pundits were launched on a quest to prove that Obama's candidacy was undone before the slightest credible evidence emerged to support their case (they were stunningly wrong, as we now know), and Clinton was only too happy to embrace a wild long-shot electoral strategy of trying to stoke white resentment against a strange, dark, foreign, religiously suspect crypto-Communist who hangs out with sundry terrorists when not spewing elitist contempt for good, decent, ordinary folk. And what happened to Clinton's black support? It plummeted by a catastrophic 44.6 percent between the bookends of the Wrightmare (and nearly a full fifth just between Pennsylvania and Indy/NC), to the point where Hillary Clinton can barely attract half the level of black support of George Allen in his 2006 senate campaign (8.2 percent versus 15). Repeat: barely half the black support of George "Let's welcome 'Macaca' here to the real world of Virginia" Allen. All the while Obama's black support rose.

It's sort of incredible that this needs to be said, but future aspiring presidents, observe the ruins of the House of Clinton and take note: If you want to be the Democratic party's nominee, you will need some black votes, and 0 percent is worse than 5, which is worse than 10, which is worse than 20. So avoid basing your campaign on the argument that your party's most loyal constituents are worthless. They will (eventually) notice.

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How I crunched the numbers: South Carolina is taken as a theoretical starting point, representing the performance among black voters Clinton could have managed even after the emergence of an electable black presidential candidate and her campaign's tactical decision to royally piss off a lot of black people. I track Clinton and Obama's subsequent performance on the four multiple-primary nights since South Carolina --- Super Tuesday, the Potomac Primary, Texas and Ohio, and Indiana and North Carolina --- by calculating the total number of votes cast by African-Americans on each election day and the share of the aggregate African-American vote each candidate received (that way, e.g., Obama's 86 percent in Delaware, 66 percent in Massachusetts, and 61 percent in New York, are weighted to reflected the tiny, medium, and huge populations of each state; for similar reasons as well as the distorting effects of political machines in individual states, I treat single-state primary days as statistical noise and ignore them). Figures are generated from the Real Clear Politics state voting totals and CNN's exit poll estimates of black turnout and vote shares. No caucuses were included since primary and caucus voting pools are incommensurate and too few caucuses had data on black voting to allow for a separate graph of black voting trends in caucus states. Likewise, the New Mexico, Oklahoma, Rhode Island, Vermont, and Washington, D.C. primaries had no available data on black voters.

You can download the spreadsheet here and double-check me, or if you're curious and industrious, plug in new values in the C, D, and E columns and track the voting trends of any demographic group.