PITTSBURGH (KDKA) — The Legislative Redistricting Commission adopted a preliminary map Thursday for Pennsylvania’s 50 state Senate districts and 203 state House districts.

The commission made many changes in House district lines, leaving several incumbents to compete against each other.

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Unlike congressional redistricting, a five-member commission draws up the district lines for the state House and state Senate. On Thursday, the commission approved a preliminary map for both chambers, and its map for the state House pits eight local incumbents against each other in four new districts.

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Drawing the 50 state Senate seats was apparently a lot easier for the commission, which approved the preliminary map unanimously, 5-0.

While there are some changes in the region, none of the incumbent state senators are forced to run against each other.

That’s not true in the state House, where smaller districts are acutely affected by population shifts.

“The population has shifted significantly from the western part of our state to the southeast,” noted Rep. Joanna McClinton, the House Democratic Leader and a commission member. “The number of Pennsylvanians living in urban and suburban communities has grown significantly, while some of our rural counties have declined in population.”

On a 3-2 vote with both Republican leaders opposing, the commission adopted a House map that Republicans called a partisan gerrymander.

“Twelve Republican incumbents will be pitted against each under this map, when only two Democrat incumbents face each other,” said Rep. Kerry Benninghoff, the Republican House Majority Leader and a commission member.

“I see this map as extremely partisan gerrymandering,” Benninghoff said. “For all the groups that have come in and talked about that, I hope we will see some responses regarding it.”

McClinton said the commission was just correcting the Republican gerrymanders of decades past.

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“I believe that the House (map) fairly accounts for the dramatic demographic changes in the population of the commonwealth since the last reapportionment,” she said.

While it’s true that statewide, 12 Republican incumbents are facing off against each other, in this region both Republican and Democratic incumbents are forced to run against each other.

For example, Republican Rep. Lori Mizgorski, of Shaler, could face Democratic Rep. Sara Innamorato, of Lawrenceville; Republican Rep. Carrie Lewis Delrosso, of Oakmont, versus Democratic Rep. Tony Deluca, of Penn Hills; and Republican Rep. Parke Wentling, of Greenville, versus Democrat Rep. Mark Longietti, of Hermitage.

The one-party battle in this region features Rep. Mike Puskaric, a Union Republican, against Rep. Jason Ortitay, a Cecil Republican.

Mizgorski said her new district rips Shaler from its suburban neighbors to put them in a city district, now represented by Innamorato.

“The Route 8 corridor really connects this district,” Mizgorski said. “The heart of the district runs up through it. Shaler, Hampton, and Richland are communities that are very much alike. Many families and friends live across the three communities.”

Innamorato defends the new district, although she said the changes hurt her, too.

“I lose the community I grew up in, Ross Township, and it hurts,” Innamorato said. “But it’s also a new opportunity to serve people around the region who are doing good things.”

This map is preliminary. Citizens have 30 days to comment before the commission finalizes the plan in January.

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It’s not clear yet whether this process can be completed in time for candidates to file nominating petitions by mid-to-late February.