Maine has taken on a somewhat bluer tinge since the 2014 gubernatorial election, as more voters register as Democrats than Republicans or independents.

Yet statewide voter registration data reveals a more complicated — and consequential  —   shift, with much of rural Maine becoming increasingly Republican even as more populated pockets of the state lean farther to the political left.

In sheer numbers, independent or unenrolled voters still constitute the largest voting bloc in Maine headed into Tuesday’s gubernatorial, congressional and State House elections. Their numbers have been shrinking, however, at a time when politics nationally and in Maine has become increasingly partisan.

As of Sept. 28, 34.9 percent of Maine voters chose not to affiliate with any of Maine’s four official political parties compared to 37.2 percent of voters in November 2014. While unenrolled voters still outnumber all other groups, Democrats are closing that gap  —   rising from 31.6 percent to 33.1 percent of registrations — as the party added 27,310 new members between November 2014 and this past September.

Republican ranks also grew but by a smaller margin, adding 13,778 new enrollees — roughly half as many as Democrats — and accounting for 27.4 percent of all registrations statewide. Part, but not all, of that slower growth is likely attributable to the fact that the Libertarian Party of Maine — whose membership skews more toward the Republican side — was allowed to begin enrolling voters in 2016. Libertarians now comprise 0.5 percent of all registrations, or 5,554 voters.

The number of registered Green Independents grew by 1,667 during that time but the Greens’ share of the electorate has held steady at 4.1 percent.

Blue versus red

The trend is not uniform statewide, however, and the regional differences largely follow the separation lines between the oft-discussed “two Maines.”

For instance, every southern and coastal county with the exception of Washington County turned a deeper shade of blue as Democrats grew their base during the past four years.

Not surprisingly, the bluest county in the state — and getting bluer by the year — is Cumberland, whose status as a liberal hot spot has only intensified as younger, wealthier and better-educated people relocated there from elsewhere. Nearly 40 percent of Cumberland County voters are enrolled in the Democratic Party versus 23 percent in the Republican Party, and the gap is widening.

Yet even in Lincoln County, which until this year has consistently been Maine’s oldest county demographically, the shift toward the center or left is visible. Republicans still outnumber Democrats in Lincoln County but just barely, and the percentage of voters enrolled in the Republican Party shrank during that time while the percentage registered as Democrats increased.

Head into interior and northern Maine, however, and the color palate shifts.

Democrats lost ground to Republicans in Androscoggin and Oxford counties since the last gubernatorial election. Kennebec County still leans slightly left  — with 32.1 percent of voters enrolled as Democrats compared to 28.8 percent as Republicans — but Republicans registered more voters than their counterparts in four years.

Republicans not only outnumber Democrats in Piscataquis, Penobscot, Somerset, Franklin and Washington counties, but the party grew its ranks faster than Democrats in each since November 2014.

Piscataquis, which was the only county in New England to vote for John McCain in 2008 and supported President Trump over Hillary Clinton 57 percent to 33 percent two years ago, continues to hold claim to the reddest area in Maine. Thirty-six percent of registered voters were Republican as of late September, compared to 25 percent Democrats.

The only exception to the urban-rural divide in Maine was Aroostook County. The County remains slightly more Democratic than Republican (32 percent to 30 percent) but Republicans gained enrollees while Democrats lost numbers during the past four years.

More partisan

Party registrations normally increase in Maine ahead of competitive gubernatorial primaries because only enrolled voters can cast ballots. In 2014, both incumbent Republican Gov. Paul LePage and his Democratic challenger, U.S. Rep. Mike Michaud, were unopposed in their respective primaries.

But Brian Duff, a University of New England political science professor, noted that as partisanship deepens nationwide, the dividing line between the two parties has become clearer for some voters. So Duff said he was not surprised that Mainers would be “sorting themselves” along partisan lines at a time when the parties have starkly different messages on issues such as immigration and the economy.

And then there’s the reality that independent or unenrolled doesn’t necessarily mean the person is in the dead center.

“The vast majority of people who call themselves independent, if you ask them … will say that they lean toward Democrats or Republicans,” Duff said.

Changing demographics likely play a role as well.

According to the latest Census Bureau figures, the overall population of Maine increased by just 5,651 people between 2014 and 2017. All eight of the state’s 16 counties that experienced growth during that period – Cumberland, York, Waldo, Kennebec, Sagadahoc, Androscoggin, Oxford and Lincoln – are located in southern, coastal and southern-interior Maine.

Cumberland and York counties alone saw their populations grow by roughly 8,200 people, while Penobscot and Aroostook counties combined lost nearly 3,300 residents. In other words, the areas with historically higher proportions of left-leaning residents are experiencing population growth while some — but not all — areas that lean Republican are losing population.

But State Economist Amanda Rector, whose office tracks and analyzes demographic trends for economic purposes, noted that Maine experienced an in-migration surge, of sorts, of roughly 7,000 people between 2016 and 2017. And unlike in past years, 13 of Maine’s 16 counties reported population increases during that year.

With the nation’s oldest population and low birth rates, Maine would need to sustain that in-migration over the long term to address what Rector’s office says are “innumerable challenges” to the economy. According to her office’s most recent report, all 16 Maine counties and all but one of the state’s largest cities — South Portland — are projected to lose population by 2034.