Editor’s Note: This is the third in a three-day series of stories drawing on the results of a statewide poll commissioned by the Portland Press Herald/Maine Sunday Telegram on the major candidates and issues on the Maine ballot Nov. 6.

In southern and coastal Maine, there’s no doubt where voters stand: They overwhelmingly support President Obama and his signature health care reform law, and they want same-sex marriage to be legal in the state by more than a 2-to-1 margin.

It’s a different story in the rest of the state.

Obama is leading Republican Mitt Romney in the north and west, too, but not by much. Those voters have a poor opinion of the health reform law and say they are just about evenly divided on the idea of allowing gay couples to marry.

The political divide between Maine’s two congressional districts is clearly revealed in these and other results of a statewide Critical Insights poll conducted in mid-September for the Portland Press Herald. The south and coast are far more liberal than the north, especially on social issues such as same-sex marriage and abortion, the poll said.

At the same time, new U.S. Census Bureau data reveal the underlying economic and social differences between the two regions — including higher incomes in the south and higher poverty in the north and west.

Economists and others first noted the “Two Maines” phenomenon decades ago, but the divide now appears to be more acute than ever, said Richard Barringer, a research professor emeritus at the Muskie School of Public Service in Portland who began warning about the diverging economies in the 1980s.

“The politics of the two districts have now grown apart,” Barringer said Monday.

Maine’s 1st Congressional District includes the more urban south and a sliver of the state that extends up the coast. The 2nd District includes the vast and mostly rural central, northern and western region of the state. While the two districts have nearly identical populations — about 650,000 people each — the 2nd District covers about 80 percent of the state’s land mass.

The two districts clearly have some things in common. Voters in both say they are struggling financially and deeply worried about the lack of jobs and the weak economy, for example.

Politically speaking, however, Maine’s 1st District looks much like Massachusetts or New York, according to the poll. Maine’s 2nd District looks much like the swing states of New Hampshire, Pennsylvania or Ohio.

The divide has become an important factor in Maine elections, and it could be again in November.

In 2009, it was strong opposition in the rural counties of the 2nd District that overturned Maine’s first law allowing same-sex marriage. And in 2010, it was the support of voters of the 2nd District that put Gov. Paul LePage in the Blaine House and a Republican majority in the Legislature.

The divide will be closely watched next month when Maine voters decide whether to approve a new same-sex marriage proposal. And some political observers say the political gap could make history this November, with Maine’s two congressional districts possibly backing two different presidential candidates and splitting the state’s electoral votes.

The notion of Two Maines has been a politically sensitive subject since Barringer and others started talking about it in the 1980s. Politicians publicly dismiss the idea as divisive, although at the same time emphasizing issues such as gun control in southern Maine and the Second Amendment in northern Maine.

“Politicians are very sensitive in this state not to make too much of this Two Maines thing,” said Kenneth Palmer, political science professor emeritus at the University of Maine. “(Maine) has got a distinctive history and a distinctive culture and I think politicians want to retain that. … We don’t have a long tradition of regional differences and regional conflict.”

Decades ago, Maine had a singular identity and the Piscataqua River was a clear barrier separating the Boston metropolitan area from Maine’s more industrial economy and traditional, rural culture. Portland had more in common with Augusta or Bangor than with Portsmouth, N.H.

Change accelerated in southern Maine in the 1980s, with people and service-sector employers moving up into southern and coastal Maine.

“Southern Maine was starting to look like the outer edges of the Boston metro area and northern Maine was still kind of traditional,” Palmer said. “There was a sense that southern Maine was kind of going off in another direction and northern Maine wasn’t going with it.”

While southern Maine developed, northern Maine saw its industrial base decline. Paper mills and pulp mills closed or scaled way back, and the fisheries that supported the Downeast region declined or collapsed.

Without the same influx of outsiders, the 2nd District remained more traditional and socially conservative. Seventy percent of 2nd District residents were born in Maine, compared with 58 percent of 1st District residents, according to the census.

Barringer said he and others started talking about the Two Maines to focus attention on the need for an economic development plan for the entire state. While political leaders have tried, it’s clear the divide has grown, Barringer said.

“In the absence of real serious policy attention to those questions, it was going to persist and deepen, and that has happened,” he said.

Many voters themselves are quick to point out the differences.

Jane Russo of Saco is in many ways a typical 1st District voter. The 50-year-old mother of two doesn’t consider herself very liberal, but she supports the same-sex marriage proposal and plans to vote for Obama.

Russo objected to Romney’s comments about 47 percent of Americans who don’t pay taxes and are dependent on government programs. “Included in the 47 percent are an awful lot of people who do work and work hard, but maybe they don’t have the education and skills to have a job to get by on,” she said.

Russo also said she learned first-hand about the more conservative culture of the 2nd District when she lived in Somerset County for 12 years. She was once told she should not get a management job because she was a woman, Russo said.

“I was taking the job away from a man who needed it to support his family,” she said. “This was said right to my face.”

John Wilkinson, a conservative voter in the Aroostook County town of Littleton, supports Romney and opposes same-sex marriage. He said he feels at home in the quieter, more rural and traditional 2nd District.

“Southern Maine is as blue as the state is long and northern Maine is all red. You could draw a Mason Dixon line right across Bangor,” he said.

Wilkinson said he believes southern Maine is more liberal because of the number of people there who are dependent on the government for assistance.

“I think there’s a lot of people (in southern Maine) that feel if the government is going to give me a handout, I’ll take it,” he said. “Up here, we’re going to work for what we need. We’re going to get our hands dirty.”

It is clearly harder work to earn a living in Maine’s 2nd District, where the median household income is $39,938, more than $13,000 less than the median household earns in the 1st District.

But census data show that a higher percentage of 2nd District residents have incomes below the poverty line and rely on cash assistance, food stamps and MaineCare.

And, while the 2nd District is clearly more conservative than the first, it is by no means a Republican stronghold, according to the poll.

Asked which of the two major political parties best serves their interests, 2nd District voters were nearly evenly split between the two parties. First District voters chose the Democratic Party by 50 percent to 30 percent.

The 2nd District also has voted for the Democratic presidential candidate in the past five elections, although it has been closer each time than in the 1st District.

It is not that Democratic politicians can’t win elections in the 2nd District, but Democrats tend to be more conservative in the 2nd District than in the first, said Palmer, the UMaine professor. “The differences are inside the parties, not between them,” he said.

Republicans, however, are hoping the more conservative 2nd District will break away and vote for Romney in November.

Obama leads Romney by just 5 percentage points in the 2nd District, compared with 28 percentage points in the 1st District, according to the poll.

Winning the 2nd District would give Romney one of Maine’s four electoral votes. It would be the first time in 184 years that Maine has split its electoral votes.

It also would focus a lot more attention on the state’s growing social and political divide, experts said.

Staff Writer John Richardson can be contacted at 791-6324 or at: jrichardson@pressherald.com