They moved more Democrats into the area by shifting it north to the Wisconsin state line and west to the McHenry County border.
Two Democrats have announced bids here so far: former MoveOn.org organizer Ilya Sheyman and businessman Brad Schneider. Sheyman has the backing of Howard Dean, but Schneider is the local party favorite.
Dold is also more conservative than his predecessor, now-Sen. Mark Kirk (R), on some social issues. That could give many voters pause and, combined with the new territory, could be enough to knock him out of office after a single term.
Incumbent: Judy Biggert (R)
7th term (64 percent)
Rating: Leans Democratic
All signs point to Biggert running again in this district. Even though she's started circulating petitions to run here, she has not confirmed where she'll seek re-election.
There's a reason Biggert is leading the charge on the GOP lawsuit. Democrats carved up her current, Naperville-based district with a vengeance.
Biggert's home is in the 5th, but almost 50 percent of her Congressional district is in the new 11th.
Former Rep. Bill Foster (D), who lost his seat in the GOP wave last year, announced he'll seek this seat too. He represented about a quarter of this district during his short tour in Congress.
Biggert is better known in the area, but it's still friendly territory for Democrats.
Open Seat: Jerry Costello (D) is retiring
Rating: Leans Democratic
Costello's departure creates an opportunity for Republicans in southwest Illinois. But it's just that — a chance in a marginally Democratic district. Nonetheless, it's one of the few bright spots for Republicans on the new map.
Here's the good news for the GOP: A few Republicans have already expressed interest in the seat, including 2010
Lt. Gov. nominee Jason Plummer, former Belleville Mayor Roger Cook and nurse Theresa Kormos. The National Republican Congressional Committee demonstrated a willingness to invest here by running advertisements blasting the 12-term Democrat earlier this cycle.
Now here's the bad news for Republicans: This is an expensive district with a solid Democratic bench. Candidates and committees will have to raise serious money to compete in the pricey St. Louis media market.
What's more, former state Rep. Jay Hoffman (D) has not ruled out switching races to run here instead of in the 13th district. Hoffmann spent millions of dollars in this media market over the course of his long career in the state Legislature.
Incumbent: Timothy Johnson (R)
6th term (64 percent)
Johnson, one of Capitol Hill's quirkiest characters, will have his first tough race in a decade thanks to the Democratic redraw. He is often seen pacing through the halls of the Capitol on his cellphone, attempting to call every constituent.
He's going to have to get a new address book next year. Johnson's chosen district includes mostly foreign territory for the downstate Republican.
Democrats moved most of Johnson's current territory into the 15th district and switched around parts of Champaign so that Rep. John Shimkus (R) could run in the 15th instead.