• In Johnson County with 116,000 people, Obama got 52% of the vote to Hillary's 20% (Edwards got 24%.) The census figures show that only 8.5% of the population is over 65 (compared to 14.6% state wide), the white population is 89.9% (compared to 94.6% state wide)with higher percentages of African-Americans and Asians than state-wide. The percentage living below the poverty line is 12.3% compared to 10.5% state wide.

• In the even larger Polk County, with 409,000 residents, only 11% are over 65 (14.6% state wide), the white population is 89.9% (compared to 94.6% state wide) and the African American population is 5.2% (compared to 2.5% state wide.) It's Asian population is 3.1% (compared to 1.6% state wide) and its hispanic population is 6.2% (compared to 3.8% state wide.)

• There's similar demographic variations with a big Obama win in Scott County with 162,000 residents, where 6.4% of the population is African American (compared to 2.5% state wide) and which has fewer elderly people and more people below the poverty line than state wide.

• Linn County with 201,000 people was also a big win for Obama, although the demographic variations are not as pronounced as the other counties.

The largest county Hillary won seems to be Cerro Gordo where she got 39% of the vote to Obama's 30%. (Edwards also got 30%.) It has 44,000 residents, with a higher elderly and white population and lower African American population than the Iowa average.

While Iowa is overwhelmingly white, Obama got his biggest numbers in the counties with larger (less rural) populations that have more minorities and fewer elderly than the state wide average.

(I didn't do a big Edwards comparison, but check out Jasper County where he won big -- it too has fewer minorities and more elderly residents than the state average.)

This might not bode well for Hillary in South Carolina, regardless of the state's past support for Bill -- and other southern states as well. The Wall St. Journal reports today that almost half of South Carolina's voters likely to vote in the Democratic primary are African-American.

This is especially pressing in South Carolina, where as many as half of the voters in the Jan. 26 Democratic primary are expected to be black. Last summer, Mr. Obama trailed Mrs. Clinton among South Carolina's black voters, according to a Clemson University poll, but in recent weeks had taken a slight lead. At the same time, the number of undecided blacks has grown, demonstrating the wide-open status of the state's primary. Black voters are also likely to be critical in the rush of later primaries. Blacks make up 40% of Democratic primary voters in Georgia, a third in Virginia and a quarter in Tennessee. They also make up a fifth of primary voters in New York and 15% in Delaware and Ohio.

Obama is already making his move there.

Friday, some members of the Obama campaign said they began reaching out to black supporters of Mrs. Clinton in an effort to persuade them to switch sides.

South Carolina State Rep. Todd Rutherford, an early Obama backer, said he started calling black supporters of Mrs. Clinton and John Edwards -- as well as those of Joseph Biden of Delaware and Connecticut's Chris Dodd, who dropped out of the race after poor showings in Iowa. Mr. Rutherford said the campaign expects to announce a list of new endorsements from black South Carolinians as early as Tuesday. "I tell them, you don't want to be on the wrong side of history," he said. ....

Rutherford predicts Obama will "run away" with South Carolina. Another state senator disagrees:

"Not only have we not lost them, they are more energized than ever," said state Sen. Darrell Jackson, one of Mrs. Clinton's political consultants and the pastor of a Columbia, S.C., megachurch.

Mr. Jackson said he rejects the idea that Mr. Obama will get a boost among black South Carolina voters simply because of race. "We want an America where we go in that booth and we don't consider color," Mr. Jackson said. "When we say that race and color and gender should not matter, that also has to apply to African-Americans when they view other African-Americans. I would not want a white South Carolinian to go in the booth and say, 'I have got to vote for one candidate on the basis that they're white.' "

The experience factor and the youth card also come into play here.

Mr. [Andrew]Young, the civil-rights leader and former Atlanta mayor who has endorsed Mrs. Clinton, said in an interview Friday that Mr. Obama has "all the raw materials" and would be his candidate of the future, but only after Mrs. Clinton.

Mr. Young said he still believes Ms. Clinton is the most prepared candidate and "the only one tough enough to stand up to the assault that is inevitable in the general [election]." Mr. Young said the Iowa results were "tremendous" due to the unexpectedly large turnout, particularly among younger voters.

"Unfortunately, since a lot of them are young people, they tend to get what we used to call 'Freedom High,"' he said. "They get excited about something but can't sustain it. I hope that this is sustainable."

The factors are out there: Race, youth and a promise of change vs. a known quantity with experience. Now we just see how it plays out. South Carolina will be very interesting.