A lot of Kentuckians are going to get new representatives in the U.S. House because of significant shifts in the state's population.
The eastern and western ends of the state lost population between 2000 and 2010 while the middle third grew, according to U.S. Census figures released this week.
Three of the state's six congressional districts fall short of the necessary population, while the other three are over it.
The national average for a U.S. House District will be 710,767.
However, the target number will vary by state; dividing Kentucky's population of 4.3 million by six seats means a population target for each district of about 723,000.
Federal law requires nearly identical populations in each U.S. House district, and state law requires legislative districts to be roughly equal.
That means it's certain the boundaries of Kentucky's U.S. House districts, as well as many state House and Senate districts, will change.
There are many potential ways to cut the pie. That's why redistricting often causes much political heartburn.
"I think redistricting by its very nature has always been and will always be a contentious political issue," said state Sen. Damon Thayer, R-Georgetown, chairman of the Senate committee that typically handles redistricting.
The new census figures show the 5th Congressional District, in Eastern and southern Kentucky; the 1st District, an oddly shaped political creation that runs from the Mississippi River to Lake Cumberland; and the 3rd District in Jefferson County fall short of the necessary population for congressional districts.
The 5th District is more than 53,000 people under the mark; the 1st more than 36,000 short; and the 3rd is about 1,600 short.
Legislators will have to make those districts bigger, moving counties from districts with too many people.
Central Kentucky's 6th District, which includes Lexington, is nearly 36,000 over the new average. The 2nd District, which includes Bowling Green, Owensboro and Elizabethtown, has nearly 37,000 people too many.
The fixes aren't easy because county populations don't add up neatly. Redistricting is something like handling a balloon filled with water: push down one spot and another pops up.
For instance, switching Casey, Russell and Adair counties from the 1st District to the adjacent 5th would get the 5th close to the required level, but leave the 1st even further short than it is, requiring more changes elsewhere.
"There are a lot of options out there, and it's going to be very challenging," Thayer said.
Legislators can split counties to equalize U.S. House seats, but Thayer said he would like to avoid doing so.
One big question the new numbers raise is whether Warren and Daviess counties can both remain in the 2nd Congressional District.
Warren County was one of the fastest growing in the state from 2000 to 2010. It is now the fifth most populous county in the state, and the county seat, Bowling Green, is the state's third-largest city.
Daviess County is among the 10 biggest counties, and so is a third county in the district, Hardin.
State lawmakers left Warren and Daviess counties together in the 2nd District after the 1990 Census because that was the wish of William Natcher, the venerable Democrat who had represented the district since 1953.
But leaving Daviess in the 2nd District required pushing the 1st from the flat farmland along the Mississippi River nearly to Central Kentucky, covering two-thirds of the state's southern border
James H. Weise, 2nd District Republican chairman, said there was no reason for that other than old-fashioned political gerrymandering.
"It's just stupid, in my opinion," Weise said.
He said lawmakers are likely to give a good deal of deference to what the state's federal representatives want.
It's not clear when lawmakers will take up redistricting.
The precinct-level numbers they need to draft a plan won't be available until July, said state Rep. Mike Cherry, D-Princeton, chairman of the House committee that usually handles redistricting.
But Thayer said he already has been talking with legislative staffers about the issue.
Thayer outlined the possibility of getting a redistricting plan ready for lawmakers to vote on early in the session that begins in January 2012.
Ideally, they need to approve a plan before the Jan. 31 deadline for candidates to file for a host of offices.
House Speaker Greg Stumbo, D-Prestonsburg, and House Minority Leader Jeff Hoover, R-Jamestown, said Friday that they would prefer to handle the issue in a special session after the November election and before the 2012 regular session.
Stumbo said if the legislature waits until January to re-draw the lines, it would probably have to move back the deadline to file for offices.
When the legislature tries to address redistricting in a regular session, it can become cumbersome, Stumbo said.
"Until it's resolved, you can't move forward on anything else," Stumbo said of redistricting. "It's probably the hardest thing that we do."
There would be only a short window for a special session after the election but before the holidays.
"I would prefer to do it during a special session, but I don't know how realistic that is," Hoover said.
Beth Musgrave contributed to this article.