Sen. Hillary Rodham Clinton won Pennsylvania on Tuesday in large part because she kept Sen. Barack Obama from burying her in Philadelphia and did much better than expected in the suburbs, targeted by both sides as the key battleground.

Obama needed to offset Clinton's strength elsewhere by rolling up big margins in the city and carrying the suburbs - homes to large numbers of the African American, affluent and college-educated Democratic voters who coalesced behind Obama elsewhere.

Instead, Clinton clobbered Obama by a 2-1 ratio in Bucks County and carried Montgomery County, albeit narrowly. Obama scored impressive victories in Delaware and Chester Counties, winning each by 55 percent to 45 percent.

Delaware County "has the inner-ring suburbs with a significant number of African Americans who voted for a great African American candidate," Gov. Rendell told reporters yesterday. "That was the difference. If you're a Democrat in Chester you're a liberal, [or] if anything else a Republican or independent. It has the most liberal of all Democrats."

Tuesday's total turnout statewide in the Democratic primary was 54 percent of eligible voters - which may match the previous record of just under 55 percent in 1980, according to state election figures.

Overall, Clinton won 51.6 percent of the 434,000 votes cast in the four suburban counties.

"His only chance of winning the state was to win big in the Philly suburbs, and he fell down there," said G. Terry Madonna, director of the Franklin & Marshall College poll. "It was stunning."

Obama won in the Main Line communities of Lower Merion, Radnor and Tredyffrin, as well as in Rose Valley and Doylestown. But he lost in the Newtown townships (both the one in Delaware County and the one in Bucks County), and also in Upper and Lower Makefield.

Clinton, meantime, racked up solid majorities in many of the classic, post-World War II suburbs, including Bensalem, Bristol Township, Warminster and Warrington, Upper and Lower Southampton, and Springfield (Delaware County).

Analysts said that female voters in the suburbs rallied around Clinton. Women made up 58 percent of the Democratic primary electorate statewide, and they favored Clinton by 14 percentage points.

EMILY's List, a group aimed at electing more women to political office, targeted 150,000 women in Southeastern Pennsylvania with four pieces of pro-Clinton mail and five phone calls each. Rep. Allyson Y. Schwartz, whose district includes Northeast Philadelphia and a large portion of Montgomery County, headed an aggressive outreach program to mobilize female voters for the Clinton campaign.

"I think women in the suburbs looked at Hillary Clinton and saw somebody who was working hard and was somebody they could relate to," Schwartz said.

David Sweet, a Harrisburg lawyer who advised Obama, said the campaign needed a victory in the suburbs. "Just as the African American vote seems to be coalescing around Obama, I think there is increasing sentiment among a high percentage of women to support Hillary," Sweet said.

In addition, analysts believe that Obama lost some Jewish voters because of Clinton's strong stand on protecting Israel from Iranian attack, as well as uncertainty over the relative newcomer from Illinois. Exit polls showed Clinton won Jewish voters 57 percent to 43 percent statewide.

John J. Kennedy, associate professor of political science at West Chester University, said many analysts mistakenly assumed that Philadelphia's suburbs are all well-to-do and full of the kinds of college-educated voters who favored Obama in previous elections.

Suburban residents do not conform to the stereotype of Starbucks-drinking and SUV-driving, he noted. Many small boroughs scattered from Eddystone to Norristown to Royersford to Bristol are predominantly blue-collar and have aging populations - two groups that have gone with Clinton.

"You look at the numbers among white, working-class communities - Obama got devastated," Kennedy said. "No wonder he got on the plane to Indiana . He needed to get out of the state."

Still, Obama got 65 percent of the vote in Philadelphia, which looked impressive in the tallies but fell short of the higher share - perhaps 70 percent - that he had hoped for.

Voter enthusiasm in the suburbs was high - higher than in the state, on average. The four suburban counties have not quite 17 percent of the registered Democrats in Pennsylvania, but they cast 19 percent of the statewide vote.

Jack Treadway, a political scientist at Kutztown University who closely follows state politics, said that, overall, Obama may have fallen short of his goal in the suburbs - and statewide - because of the clear racial pattern in the vote.

"We don't want to call voters racists," he said, "but the reality is that it did break down on racial lines. . . . You're going into areas [in the suburbs] that are more affluent and have better educations - he should have done better there."

Exit polls showed that Obama won the support of 9 out of 10 black voters, while two-thirds of white voters went for Clinton.

Bucks County, Clinton's strongest in the suburbs, has the lowest proportion of black residents - 3.6 percent, according to a 2006 Census estimate.

Delaware County, which went with Obama, has the highest proportion of black residents - 18.4 percent.

But sometimes the pattern breaks down.

Chester County, which gave the exact same share of its vote to Obama as Delaware County, is just 6.3 percent black. But Chester residents have higher-than-average household income and education, both factors that benefitted Obama.

The exit poll of Pennsylvania voters found that 16 percent said race was a factor in their decision, though that was not out of line with results from other states, such as California and Ohio. "There were plenty of whites who supported Sen. Obama," Rendell said. "I don't think it was a factor that affected the outcome."

Montgomery County Democratic chairman Marcel Groen had a simpler explanation for Clinton's win in his county: She showed up. A Clinton - either the candidate, her husband, former President Bill Clinton, or their daughter, Chelsea - was in the county an average of three times a week. Obama and his wife, Michelle, made two or three appearances during the entire six-week campaign, he said.

"People forget how important personal contact is," Groen said. "Nothing is more important than being wanted."

Contact staff writer Thomas Fitzgerald at 215-854-2718 or tfitzgerald@phillynews.com.