AUGUSTA — When the time comes to draw the boundary line that separates Maine’s two congressional districts, the portion that has been redrawn the most in recent decades is the line that runs through the heart of Kennebec County.

And while Maine’s bipartisan Apportionment Commission — charged with the task of establishing district lines for county, state and federal election districts — is directed to the extent possible not to split counties between districts, Kennebec County remains divided, but in an entirely new way under the recently approved plan.

Following the commission’s work, Augusta, Chelsea, Farmingdale, Hallowell, Manchester, Readfield and Winthrop have been shifted into the 2nd Congressional District. Most of those municipalities lean or are strongly Democrat, with the exception of Chelsea and Manchester, where Republicans outnumber Democrats among registered voters.

Albion, Benton, Clinton, Litchfield and West Gardiner, all Republican leaning or strongly Republican, are moving to the 1st Congressional District.

Why Kennebec County is split in this way when none of Maine’s other 15 counties are is probably a matter of negotiation.

James Melcher, a political science professor at the University of Maine at Farmington, said keeping the split in one county makes it easier to reach compromise under the bipartisan system that Maine has, and it’s a function of decisions that were made a long time ago in establishing the congressional districts.

“I would say that this is a function of Kennebec County being in the middle of things, having enough moveable parts that each party’s got things it wants and that you need to come up with something that you can get a supermajority for,” Melcher said, “and that means you’re going to need both parties to play ball.”

Ever since Maine achieved statehood in 1820, its congressional district borders have been all over the map. While the state currently has two districts, it once had as many as eight. Until 1962, Maine had three.

The reason that the lines were drawn where they are dates back to a time when redistricting in Maine was a partisan exercise and Republicans held the majority in the Legislature and also held the Blaine House.

Paul Mills, an attorney in Farmington and a political historian, said when the districts were being established, the Democratic leaning Androscoggin County was slotted into the more rural and more Republican 2nd District and away from the neighboring Democratic strongholds of Portland, Saco and Biddeford in Cumberland and York counties.

“The two leading Democratic areas in 1961 were York and Androscoggin counties,” Mills said. “If they divided the Democratic strongholds and put one in the second district, and Portland and Biddeford area in the first, then chances are they would have Republicans (elected),” he said.

Those lines have remained intact. But Kennebec County, the northernmost county in the 1st District, tends to be divided in different ways between the two districts because of its proximity to the 2nd District, he said.

And Kennebec County is not alone in being split; Waldo and Knox counties have also been carved up between districts, he said.

Every 10 years state officials evaluate how Maine’s population has changed and decide how to balance the two districts by population.

“The ‘why’ is easy,” Mark Brewer, a political science professor at the University of Maine, said from his Orono office. “It’s required by the Constitution at the federal level and then the state constitution requires it as well for the state districts.”

After census results are tallied every 10 years, federal officials undertake apportionment, which is the process of determining how the 435 seats in the U.S. House of Representatives should be divided among the states based on population. In states that have lost or gained population, that can mean the loss or addition of House of Representative districts. When that happens, redistricting takes place.

In Maine, where the population has not changed significantly in the last decade, the bipartisan Apportionment Commission is charged with the task of establishing district lines for county, state and federal districts.

Much of the 2.7% growth in the state’s population has happened in the southern part of the state, which has meant that district lines have had to be redrawn to shift 23,300 people from the 1st District to the 2nd District, more equally dividing the state’s 1.2 million residents.

Brewer said one of the requirements of the process is that the congressional districts be about equal in population size.

“That’s what resulted in certain towns in Kennebec County being moved either from the first district to the second, or vice versa,” Brewer said. “The physical space doesn’t matter. It’s the number of people.”

Melcher said it seems kind of funny that Kennebec County is sliced and diced, but compared to other districts in other states where the redistricting process is run by the party in power, Maine’s congressional districts are pretty rational.

At the federal level, it’s unclear what the impact would be. The 1st District is heavily Democratic and adding a few thousand Republican voters is unlikely to shift election outcomes there. Adding some strongly Democratic communities to the 2nd District, which has shifted between parties in the last three elections, may not change much.

While the process of redistricting is inherently political, Brewer said, it’s less so in Maine, where the Apportionment Commission is bipartisan by law and requires the Legislature to sign off on the plan.

It did so overwhelmingly in the House and unanimously in the Senate at the end of September before it was signed into law by Gov. Janet Mills, making Maine the second state in the nation to complete its redistricting process.

“There was a lot of negotiating between not only Maine’s legislative leaders but also the representatives of the current members of the (U.S.) House … get involved,” he said. “While technically not having a seat at the table, they have a seat at the table.”

The outcome of redistricting means that U.S. Rep. Jared Golden, a Democrat, has picked up a net of about 3,000 voters who supported Joe Biden in the 2020 presidential election, Brewer said. That makes the 2nd District, a swing district, slightly more Democratic.

Even those relatively few votes might matter, Paul Mills said, given the close results of the 2nd District congressional race. Incumbent Rep. Bruce Poliquin, a Republican, earned about 3,500 more votes than Democratic challenger Golden in the first round of counting. But as it wasn’t a majority in the ranked-choice voting race, as other candidates were removed and their votes redistributed, Golden picked up the victory.

The loss of those communities in the 1st District is not likely to have much of an impact, as it has been a Democratic majority district and is getting more and more Democratic.

“It’s about as Democratic a lock as you can imagine,” Brewer said. “Maybe it’s not a Manhattan Democratic lock or a San Francisco Democratic lock, but it’s getting there.”

At the local level, it’s not clear the switch will have much of an impact, town officials say. They expect whoever represents them will be responsive to their requests for help.

In the last year, a new congressional earmark program has given members of Congress in both houses the ability to seek funding for projects in their districts under the Community Project Funding Program.

Keith Luke, the economic development director for the city of Augusta, said Augusta had a successful application through the office of U.S. Rep. Chellie Pingree’s office.

“Next year, we’ll continue to participate in the program,” Luke said, but the city’s submission will be submitted to Golden’s office.