Pennsylvania's high court last month became the first state court to throw out a congressional map because of partisan gerrymandering, a decision that has ignited a scramble to redraw district boundaries as dozens of candidates watch and wait.
Now, the boundaries for Pennsylvania's 18 congressional districts for May's primary election are up in the air.
Districts in which there is a retiring incumbent and particularly contorted boundaries could see the biggest changes. Meanwhile, boundaries drawn by Republicans after the 2010 census to favor Republicans are expected to become less GOP-friendly, giving Democrats nationally a boost in their quest to take control of the U.S. House.
Members of Congress, dozens of first-time candidates and millions of registered voters may find themselves living in a new district, a month before the deadline to file paperwork to run in congressional primaries.
The Democratic-majority state Supreme Court has promised to produce a new map of districts no later than Feb. 19, and substantial changes are likely in store.
Here is a look at possibilities:
WHAT THE COURT WANTS
The court could consider proposals by Democratic Gov. Tom Wolf, lawmakers and other parties to the gerrymandering case. The justices provided the same guidance that the Pennsylvania Constitution gives when drawing maps for state legislative districts: equal population, compact, contiguous and with boundaries that split as few municipalities and counties as possible.
In the court majority's 139-page opinion, Justice Debra Todd wrote that no municipalities in Pennsylvania were divided among congressional districts before 1992; 68 municipalities were split in the 6-year-old Republican-drawn map.
In addition to splitting municipalities, Republicans who controlled the Legislature and governor's office in 2011 broke decades of geographical precedent when redrawing the map.
They shifted whole counties and cities into different districts and produced contorted boundaries in an effort to protect a Republican advantage in the congressional delegation. They succeeded, securing 13 of 18 seats in three straight elections in a state where registered Democratic voters outnumber Republicans and Democrats hold a large majority of statewide offices.
Traditionally, state lawmakers draw congressional maps with an emphasis on protecting sitting lawmakers. But the court may not be interested in protecting incumbents, and Wolf doesn't seem interested in it.
"I think the incumbents will probably have a great interest in preserving their lack of competiveness," Wolf said last month.
This year, six congressmen re-elected in 2016 aren't running for another term, creating the most open seats in Pennsylvania in four decades. That could mean substantial changes for those districts.
A particularly contorted district — Republican Rep. Pat Meehan's 7th District, labeled "Goofy Kicking Donald Duck" — faces an overhaul, perhaps by packing tendrils now snaking through five counties closer to its longtime anchor of Delaware County.
Several other districts could become more compact:
— Democratic Rep. Matt Cartwright's 17th District reaches into six different counties to string together Democratic voters in northeastern Pennsylvania cities.
— Republican Rep. Ryan Costello's 6th District curves through four counties.
— Republican Rep. Lou Barletta's 11th District was sent plunging an extra 75 miles into south-central Pennsylvania from its longtime home in northeastern Pennsylvania.
— Republican Rep. Charlie Dent's 15th District, for decades in the Lehigh Valley, now stretches west 80 miles across five counties.
Meehan, Dent and Barletta aren't running for another term.
Democratic Rep. Mike Doyle's Pittsburgh-centered district is the only western Pennsylvania seat held by his party. Under a new map, that could change. Doyle's district is heavy with registered Democrats, and shifting some of those voters to districts that share Pittsburgh's suburbs — the 18th District, which is vacant after Republican Rep. Tim Murphy resigned in a scandal, or Republican Rep. Keith Rothfus' 12th District — could make all three districts more competitive.
The 12th District could become more compact. It now runs some 100 miles from the Ohio border past Johnstown in a shape the Pittsburgh Post-Gazette called "a malnourished hammerhead shark winding through six counties."
THE REPUBLICAN PROPOSAL
On Friday night, leaders of the Republican-controlled Legislature delivered to Wolf a proposal for him to consider forwarding to the court with his approval. Republicans said it complied with the court's wishes and federal law.
But Democrats quickly attacked it as a "naked partisan gerrymander." For instance, four districts remain heavily packed with Democratic voters. Democrats also suggest that Republican took great pains to protect Republican chances at winning 13 districts, working particularly to help Costello, the most endangered Republican incumbent.
In addition, the Republican map shifts the homes of two prominent first-time Democratic candidates into new districts. Conor Lamb would be moved to Doyle's 14th District, instead of the vacant 18th District. Chrissy Houlahan, seen as a dangerous challenger to Costello, would be moved to the 7th District.