By Pat Loeb

PHILADELPHIA (CBS) – Voters In Pennsylvania may be in for a surprise next month when they go to vote for their congressman.

The state legislature drew up dramatically different congressional districts after the 2010 census, so many voters will be choosing between candidates they didn’t expect to see on their ballots.

For example, Lower Merion residents may think their congressman is Jim Gerlach, but it’s actually Chakkah Fattah. Cheltenham residents may believe they’re represented by Fattah, but instead it’s Allyson Schwartz. And residents from Malvern may have thought their incumbent was Pat Meehan, but their ballot is going to give them a choice between Gerlach and Manon Trivedi.

“Districts have completely changed their boundaries,” Montgomery County democratic chairman Marcel Groens said. “When you get to the polls, you’re going to be in shock.”

Montgomery County is now divided between five congressional districts. Groens says voters may be aware of redistricting, which is done every ten years, but if they skipped the primary, like many did, they may not realize the impact.

Groens notes the odd shapes of the districts seem primarily designed to protect incumbents, which County Republican chair Bob Kerns agrees with.

“This is actually, in my mind, a very good thing,” he said.

Voters can get an advance look at their local ballot through www.smartvoter.org.