WISCASSET — The first time Sumner McKane mentioned publicly he was making a movie about old postcards, someone in the audience groaned, “Oh, no.”

McKane could only laugh. He understood.

A filmmaker, musician and historian, he was underwhelmed with the idea himself. He only agreed to spend time with the collection of early-20th-century black-and-white postcards as a favor to a friend at the Penobscot Marine Museum in Searsport, which owns the collection. He didn’t think it would lead to anything.

Instead, his reluctant dive into the museum’s vast collection of glass-plate negatives from the Eastern Illustrating & Publishing Co. opened a time capsule to a century ago and led to McKane’s third feature-length film, “The Northeast by Eastern.”

It’s a live-performance documentary about the Belfast-based company, which dispatched photographers across New England and upstate New York every spring, summer and fall for about 30 years in the early 1900s to photograph the region’s small towns, local landmarks, profitable factories and natural wonders. McKane made the movie with images from the collection, archival footage, oral histories and interviews with historians. In addition to using music from the early 19th century as a sound bed for the film, McKane scored it for guitar and bass, and he and bassist Josh Robbins accompany its screenings with live performances.

McKane will screen the movie at the St. Lawrence Arts Center in Portland on Dec. 30.

STORIES FROM MAINE’S RURAL PAST

This is his third full-length multimedia project, and all hinge on characters from Maine’s rural past. His first movie, “In the Blood” from 2010, tells the story of Maine lumberjacks and river drivers. In 2013, he made a movie called “The Maine Frontier” about Isaac Simpson, who traveled northern Maine as a barber, blacksmith and jack-of-all-trades – photographer among them.

Both are stories about industrious men who made nomadic livings using skills that were adaptable to their conditions, times and circumstances.

“The Northeast by Eastern” follows a similar storyline of innovation and a particular style of brash Yankee ingenuity. “They were all doing totally different things but following a similar thread,” McKane said.

The hero of McKane’s newest story is Herman Cassens, who owned Eastern Illustrating & Publishing. His motives were purely financial. Postcards were big business, providing tangible links among friends and family separated by distance. A century ago, they were today’s equivalent of a text or a tweet: a quick snapshot and a brief message, transmitted by the most efficient means of the time, the U.S. mail.

The preservation of history was not Cassens’ intent, but it is his legacy. Kevin Johnson, photo archivist at the Penobscot Marine Museum and the collection’s authority, believes about 75,000 of Eastern’s glass-plate negatives survived. The museum owns about 50,000 of them. Of those, 30,000 are available through the museum’s online database, and that’s where McKane took his reluctant first look.

“I had no idea about the postcards, and I was underwhelmed with the prospects. But I decided to give it a shot,” McKane said.

He did so at the request of Johnson, who hired McKane in 2015 to perform “The Maine Frontier” at the museum as part of a year-long exploration of Maine photography. Johnson appreciated McKane’s encompassing approach to his subject, and he thought the Eastern collection was worth his attention.

Johnson has dedicated the last decade of his professional life to the collection of the glass plate negatives, which after Cassens’ death in 1948 remained in storage for most of a half-century in hundreds of boxes that weighed several tons. They were stored in Belfast before being moved to Camden and later to Union Hall in Rockport, when the collection was donated to what is now Maine Media Workshops.

A water pipe burst in Union Hall in winter 2007, soaking the collection, which was stored in the basement. Volunteers dried the negatives plate by plate, and that spring the collection was donated to the Penobscot Marine Museum. Johnson has been working with the collection since 2005. He helped with its rescue and has been its primary curator and champion.

He remembers his first conversation with McKane about the project. “Sumner was not too thrilled. He couldn’t imagine how he could make something interesting out of postcards. I said, ‘Hear me out. Come see what we have.’ ”

The original idea was a short film – 10 to 15 minutes, to accompany an exhibition this past summer about the 100th anniversary of the postcard.

McKane agreed to that, and once he dug into it, he quickly understood Johnson’s dedication to and zeal for the collection.

Each spring, as soon as the roads were fit for travel, Cassens hired men to drive across New England to sell postcards. Photography was a means to an end. They focused on prosperous businesses, community events and colorful people. The photographers were given travel expenses, a salary and commissions, based on the number of postcards they sold.

The photographers traveled in cars marked with the company name and logo, and they used large-format view cameras with 5-by-7-inch glass plate negatives. The photographers sent the negatives back to the factory in Belfast, which processed them and sent postcards back to stores in the towns where the salesmen-photographers had recently visited.

At its height, Eastern produced 1 million postcards a year and was the largest producer of postcards in the eastern United States.

WATCHING HISTORY UNFOLD

Collectively, and viewed through a century of perspective, the postcards document changes to the landscape, the impact of the automobile and other technological advances, as well the stories of Prohibition and the Great Depression.

McKane’s task was making those stories interesting in a movie format. In addition to the postcards, he used oral histories and archival films in the public domain, conducted interviews with Johnson and other historians, and created music that sounds like it might have been written in the 1920s. “Each image is its own film,” he said. “There are so many details in these postcards that if you take a look longer than a glance, you can really date it. They’re true time capsules.”

There are accounts of smuggling across the Canadian border during Prohibition, of brawling river drivers and of growing up during a time without worry. The arching theme is life during a simpler, quieter time. There is nostalgia here.

In the movie, McKane quotes Audrey Thibodeau of Caribou talking about how “life was so different then. And I hate to say this, but better – better. … All we worried about was Mr. Whitney sending us out of his strawberry field.”

He borrowed that conversation from the Aroostook County Oral History Project and paired it with postcards from Caribou and period films of children sledding in the winter.

After years on the road playing in bands, making movies gives McKane an outlet for all his creative instincts while staying closer to home. He’s always enjoyed composing music and playing, but he never liked singing. “This is a way to perform and not be a front man,” he said. “It takes a load off my shoulders.”

His professional lifestyle borrows from the stories of the people he likes profiling: industrious Mainers whose skills in various fields add up to a satisfying career. McKane, 40, grew up in Damariscotta and lives with his wife and daughters in Wiscasset. He studied at Rocky Mountain School of Photography and the University of Montana, and he graduated from the University of Southern Maine with a degree in history.

He’s already deep into his next project. It’s a movie called “Speedway,” and it’s about short-track stock car racing in Maine from 1911 to the present.

McKane was exposed to racing when he was younger and started paying closer attention when his kids became interested in the summertime sounds of a racetrack near their home. They went to check it out and learned quickly that auto racing is a lot more complicated than a series of left-hand turns.

They got hooked, and McKane spent all last summer in the pits, learning the ropes and interviewing people. He’s since amassed a collection of archives from the racing community across Maine – home movies, programs, photo albums, newspaper clippings. He’s got boxes full of material at his studio in Wiscasset and is in the process of combing through it and scanning anything that might be useful for his next movie.