Montgomery County Commissioners Josh Shapiro and Leslie S. Richards pledged a new era of civility and cooperation Tuesday as they became the first Democratic duo to assume control of the county's government since the year Thomas A. Edison patented the phonograph.

Taking over from a Republican administration better known for bouts of infighting than its bipartisan policy-making, the two Democrats vowed, during a ceremony where they and nine row officers were sworn in, to change the tone of debate.

"Today, starting right now, rancor and acrimony will yield to respect and accord," Shapiro said. "We will reform our county government and make it work again."

The same new year that ushered in historic change in what was once one of Pennsylvania's most reliable Republican strongholds brought four more years of GOP control to commissioners boards in three other counties in Philadelphia's suburbs.

In Bucks, Chester, and Delaware Counties, long in Republican hands, majority-GOP boards were sworn in Tuesday as Democratic and Republican political strategists turned their attention to the 2012 presidential and congressional races.

The lineup of who took office this week in the hard-fought swing counties of Philadelphia's suburbs could foreshadow whether Pennsylvania goes red or blue in this year's election map, they said.

But for now, Richards said, excuse the Montgomery County Democrats if they paused for a day to celebrate their own arrival.

Voters ushered in Shapiro, a 38-year-old former state representative from Abington, and Richards, an ex-township supervisor from Whitemarsh, in November on pledges that included restoring the county's fiscal footing and holding the line on property taxes.

On Tuesday, describing the giddy hours after her election to a crowd of supporters, Richards, 44, recounted her young daughter Rebecca's response. Administrators at Rebecca's school asked why she had shown up late on the morning after Election Day, Richards recalled. Her daughter had replied: "We were busy making history last night."

History indeed. The last two Democrats to hold a majority on the county's three-man board - an auctioneer named Noah D. Frank and an Army captain, Jesse B. Davis - assumed office in 1878. To put that in perspective, it was the year the U.S. Senate first rallied behind the cause of women's suffrage (though its enactment was still decades away). Electricity and the telephone were just beginning their march into American households.

Shapiro echoed that Reconstruction-era spirit of expansiveness Tuesday as he welcomed input from Bruce L. Castor Jr., the board's lone Republican, during a brief organizational meeting at which the new board appointed several staff members.

"His voice will be an equal voice on this board and an important one," Shapiro said.

For his part, Castor appeared willing to cooperate.

The former district attorney gained a reputation as a vocal contrarian during the previous administration, after he was pushed out of power days before his 2008 swearing-in by an alliance struck between his fellow Republican, James R. Matthews, and then-Democratic Commissioner Joseph M. Hoeffel III.

Over the next four years, the fighting between Castor and Matthews became so frequent and hostile that it morphed into a constant issue in last fall's campaign. Neither Matthews nor Hoeffel opted to run for reelection last year.

"Since the campaign, there have been absolutely zero comments in public undermining each other," Castor said Tuesday. "I've been waiting four years to be able to say that."

Contact staff writer Jeremy Roebuck at 267-564-5218, jroebuck@phillynews.com, or @jeremyrroebuck on Twitter. Read his blog, "MontCo Memo," at www.philly.com/montcomemo.