KENNEBUNKPORT — Clad in his blue-black motorman’s outfit ”“ sleek jacket, gloves and old-fashioned rail operator’s hat perched atop his head ”“ John Mercurio sat with his arms slung back on a car-long bench seat inside a moving trolley, salvaged from decades lost to time. His name tag, dangling from a lanyard clipped to this throwback regalia, rocked gently as the trolley wound through turns and across flat expanses of land, where the town line between Arundel and Kennebunkport becomes fuzzy. Dew drops sparkled brightly on fields of grass in an overcast, late-May chill.

“Most people are not familiar with what the trolley companies did for urban transportation,” said Mercurio, walkie-talkie buzzing with static on his hip. “It changed peoples’ lives. It had a tremendous impact.”

Mercurio is a docent and manager of the Education Department at the Seashore Trolley Museum, which celebrates its 75th anniversary this year. Like countless volunteers before him, Mercurio was drawn to the museum by a simple love of the rails: the history, the industrial-mechanical romance of a streetcar rumbling underfoot. For three-quarters of a century, this unique shrine to public transportation has operated largely on the strength of volunteers, who find their way to its sprawling campus almost by instinct ”“ like moths drawn to flame.

And they know their history. Mercurio smiled as he recalled the museum’s origins.

It began in 1939 with a group of railway enthusiasts, mostly Bostonians, who dreaded the impending end of streetcar service on the Biddeford & Saco line. As recounted by James Schantz, chairman of the Seashore Trolley Museum’s board of trustees in his 2013 history entitled “A Look Back,” members of the group decided to pool their resources and purchase one of the open cars ”“ No. 31 ”“ to preserve and operate for future generations. The mayor of Biddeford agreed to the $150 purchase on the condition that the car be moved out of town. The founders of the museum settled on its current location, tucked inside forested acreage alongside what is now Log Cabin Road.

The Seashore Trolley Museum has expanded greatly in the intervening years, adding streetcars and trolleys from across the nation, as well as countries like Hungary, Italy, Japan and Australia. But the original No. 31 car from Biddeford is still a prize among the museum’s exhibits, and a reminder of its origins.

“We’re here today thanks to our founders,” said Mercurio. “And we have all this to share with the public to educate them on what the rail lines were all about.”

One of the beneficiaries of that education was Taryn McDonagh. Born in Ireland, McDonagh now lives in Boston with her husband and son, both of whom joined her recently on a fact-filled excursion along the mile-and-a-half long track looping around the museum’s tree-lined fringes. With one eye on her son, who gaped in fascination through the trolley’s windows, McDonagh listened as volunteer streetcar operator Herb Pence peppered the ride with tidbits culled from the museum’s long history: The expansion of its collection beyond the bounds of New England, coinciding with the railway industry’s gradual decline in urban centers in the 1950s; the enlargement of the main line ride in the 1970s, with track built on the former Atlantic Shore Line right-of-way toward Biddeford; the specialized equipment that was brought in to the restoration shop in the 1980s.

It was a lot to take in. Ultimately, it was the ride itself that had the most impact on McDonagh, sitting inside a working streetcar once populated by men and women from a bygone age, fedoras tipped back on their crowns and newsprint smudged on their fingertips.

“It’s such a beautiful carriage,” said McDonagh. “Growing up in Ireland, we had double-decker buses, and they were no big deal. But this ”“ this is special. The amount of work that went into these is incredible. I can’t get over how beautiful they are for public transport.”

It’s that kind of reaction that has kept Chuck Griffith volunteering his expertise for the past 39 years. A former machinist for the Massachusetts Bay Transportation Authority, Griffith is among a corps of individuals who are in charge of maintaining the aesthetics and mechanical integrity of the vast fleet of trolleys; it’s a collection that has spilled over into several auxiliary buildings peppered throughout the campus.

As with the other volunteers, his passion is ingrained.

“My family’s been in the transit business for over 100 years,” said Griffith. “Transit’s been in my blood since I was little. I followed in my father’s footsteps. It was just natural.”

With such dedication from the staff, the Seashore Trolley Museum has been making efforts to marry its historical appeal with the desires of a 21st-century audience. Enter Executive Director Sally Bates.

Over the past couple years, Bates has helped to nearly double the museum’s revenues, thanks in large part to the expansion of events and seasonal offerings, as well as the addition of new ones. One in particular will serve as a nod to history. On Friday, Aug. 22, the Seashore Trolley Museum will host its first-ever speakeasy, converting several vintage rail cars into lounges replicating prohibition-era drinking establishments, which operated under cover of secrecy. Sponsored by business partners Blue Elephant Events and Catering of Saco, and Portland’s Dogfish Bar & Grille, the speakeasy will invite adults to quaff cocktails aboard trolleys arranged in a quasi-secluded fold between two of the museum’s primary trails.

One of the cocktails will be new ”“ the Seashore 75, an homage to the museum’s 75 anniversary.

“I thought, ”˜Wouldn’t it be fun to have the cars as bars?’” said Bates, strolling through the field in which the streetcars will be placed. “But it needed a theme. That’s where the speakeasy part came in. It will be a novel use of the cars.”

Other regular events will cater to families. The expansion of autumn’s Pumpkin Patch Trolley event will feature a children’s poetry competition and pumpkin dessert contest; horses will be brought in from the Ever After Mustang Ranch. Each Wednesday in July and August, the museum will offer storytimes for children; and on each Wednesday and Thursday during those months, visitors will have the option to take a trolley ride at sunset, with ice cream available during the trek.

But when an institution celebrates 75 years of existence, an event of special magnitude is in order. On Saturday, July 5, the Seashore Trolley Museum will host its 75th Anniversary Celebration, marking the milestone with a rededication of Montreal’s “Golden Chariot,” one of the famous observation cars that operated in that city before trolley serves slowed to a halt in the middle of the 20th century. Marie-Claude Francoeur, Quebec’s delegate to New England, will attend the celebration and give remarks at 2 p.m., in both French and English. That ode to the past will intermingle with modern-day technology, as visitors explore history on touch-screen kiosks speckled throughout the grounds, with more planned for the lobby and Town House Shop.

Both Bates and Mercurio acknowledge that the bridge from past to future is built largely by the hands of the passionate volunteer corps ”“ those who proudly don the uniforms once worn by denizens of the rails, who were most alive when the wind was at their face, the floor of a streetcar rattling gently below.

“It was just because of their love of trolleys that all this has been here for the past 75 years,” said Mercurio.

And, he hopes, will be for 75 more.

— Staff Writer Jeff Lagasse can be contacted at 282-1535, ext. 319 or [email protected].