As independent and Republican voters flocked to Pennsylvania courthouses and county buildings in recent weeks to change their voting registration in advance of the state's April 22 primaries, they managed to also change generations of history: Voter registration in Bucks and Montgomery Counties, both in suburban Philadelphia, has flipped from Republican to Democratic, the New York Times reports.

The Philadelphia suburbs featured some of the most hotly contested battlegrounds in 2006. Democrats made strong bids for three GOP-held seats and beat incumbents Curt Weldon and Mike Fitzpatrick, while narrowly missing picking off Jim Gerlach's more exurban district as well. All three districts, the state's Sixth, Seventh and Eighth, voted for both Al Gore and John Kerry, though by very narrow margins, and have been trending increasingly Democratic in recent years.

Of the four counties that ring Philadelphia, Chester and Delaware Counties retain Republican registration advantages. Gerlach's Sixth District includes the outer portions of Chester and Montgomery Counties; Weldon's old Seventh District, represented by freshman Democrat Joe Sestak, is heavily centered in Delaware County; and Fitzpatrick's Eighth District, held by freshman Democrat Patrick Murphy, has all of Bucks County within its borders.

The new boon comes after Democrats lost dozens of seats in the South during the 1990s and needed to find new voters to whom to appeal in order to regain their lost majority. They found early success with appeals to suburban voters, and, in recent years, those efforts have paid off most notably around Philadelphia, the suburbs of Chicago and even exurban New York City, both on Long Island and north through the Hudson Valley.

Opportunities for the party's gains don't stop at the state's borders; along with Gerlach, districts currently represented by New Jersey Republicans Jim Saxton and Frank LoBiondo are increasingly moving Democratic as well, and when Republican Rep. Mike Castle retires Democrats will be heavily favored to take over his Delaware at-large seat.

As Republicans get used to the minority, their efforts will turn more toward searching for their own new voters to reach. Until they find that group, the GOP could see more counties, historically Republican, shift to Democratic columns.