Exit polls have shown that the contest between Hillary Clinton and Barack Obama has produced deep divisions among Democratic constituencies. It looks something like tribal warfare. Whites have voted, if you average the results from the states, 53 percent to 39 percent for Clinton; blacks, 80 percent to 17 percent for Obama; Latinos, 58 percent to 39 percent for Clinton; Asians, in California (the one primary state where they're numerous enough to gauge), 71 percent to 25 percent for Clinton.

The differences in voting by the young, overwhelmingly for Obama, and the elderly, overwhelmingly for Clinton, are as large as any I can remember in either a primary or general election. Upscale voters are heavily for Obama; downscale voters are heavily for Clinton.

As the contest has continued, increasing percentages of Clinton and Obama voters say they wouldn't vote for the other candidate against John McCain.

But the exit polls don't show another tribal division, one that emerges when you examine the election returns by county and congressional district. In state after state -- from New Hampshire and Michigan to Texas and Ohio -- Obama runs unusually strongly in counties with large universities. Academics -- and I include here those who choose to live in university towns as well as those actually in or teaching school -- seem to find Obama particularly appealing.

Also, Obama runs unusually well in many state capitals -- Concord, Lansing, Tallahassee, Atlanta, Nashville, Santa Fe, Dover, Jefferson City, Sacramento, Trenton, Madison, Columbus, Austin -- which of course have unusual concentrations of public employees (and in some cases big universities, as well).

Clinton's highest percentages come in counties with large numbers of Latinos and what I call Jacksonians. You can see the latter in counties in what is loosely called Appalachia -- southwest Virginia, southern Ohio, the north end of Georgia, non-metropolitan Tennessee, northern Alabama, northeast Mississippi, all of Arkansas, southern Missouri, eastern Oklahoma, east and central Texas.

These are lands that were settled by the colonial era immigrants from northern England, Scotland and northern Ireland and their descendants, who thronged down the Appalachian chain and then, like their heroes Andrew Jackson and Sam Houston, kept going southwest.

Clinton's strong performance among Jacksonians may reflect her positive appeal (it certainly does in Arkansas), but it also seems to reflect a distaste for Obama. Buchanan County, Va., which borders the yet-to-vote states of West Virginia and Kentucky, voted 90 percent for Clinton and 9 percent for Obama. Continued...