PHILADELPHIA-Barack Obama's projected double-digit victory over John McCain in Pennsylvania was fueled in large part by an electoral sweep of this city and the surrounding suburbs that are critical to winning statewide elections.

Obama captured the entire 5-county region, including the four suburban counties. He was projected to win a whopping 83 percent of the vote in Philadelphia proper, piling up a margin of almost 459,000 votes that cushioned losses elsewhere.

His performance in the collar counties was equally impressive. As expected, he won Montgomery County, the wealthiest and most Democratic of the four, taking it by a projected 20 points. But he also won more blue-collar, conservative areas in Bucks, Chester and Delaware counties. He was projected to win Bucks and Chester by 9 points each, while running away with Delaware by 21 points.

All told, he won more than twice the votes McCain did in the 5-county region, taking the counties by a combined 656,000 votes, according to projections. Despite winning only 18 of the state's 67 counties, his margin in the Philadelphia region exceeded his almost 600,000-vote margin of victory in the state as a whole.