There’s a certain charm to Onset, particularly its laid back atmosphere. Author Michael Maddigan says that’s been a key trait since it was founded in 1877.

“It’s always been a middle class resort. The Boston Globe, as early as the late 1880s, remarked that everyone there felt comfortable compared to more upscale beach towns,” said Maddigan.

Onset has been called “the people’s resort,” “summer home of the common people,” and “the Coney Island of the South Shore.” In Maddigan’s new book, “Onset and Point Independence,” he explores that history, illustrating it with postcards.

A Middleboro resident, Maddigan and his family spent summers in Onset. As someone with an interest in local history, he said Onset’s origins as a meeting ground for Spiritualists intrigued him. Founded in 1848, the Spiritualists believed communication with the dead was possible.

“They held seances by the ocean and it seemed kind of strange to me,” said Maddigan. “I was interested in learning more about that.”

The Spiritualists attended lectures and conferences in Onset Bay Grove, and the camp grew into a village with wooden cottages, hotels and restaurants to accommodate the community.

Maddigan said scandals that involved faked ghostly encounters damaged the group’s reputation. However, by that time Onset had earned a new reputation as a recreational hub near 1900.

Maddigan said with its bluffs, protected harbor and picturesque Wicket’s Island, the area became a tourist destination.

Some commented on the relaxed atmosphere. According to the book, “At Onset Bay camp ground a man may walk the entire length of Onset avenue…attired in nothing more than an ordinary bathing suit, and he excites no comment. A man with a silk hat and kid gloves will attract more attention.”

Some in town didn’t agree with that attitude.

“Apparently they had a problem with people wandering around in their bathing suits, and that was a problem for years,” said Maddigan. “Bylaws were passed, but there was a question of enforcement.”

The postcards depict a bustling summer season with packed beaches, boats, concerts and other activities.

Many of the postcards were from a relative of Maddigan’s, who started collecting them in 1978.

Maddigan’s interest in local history started when he was in high school as a guide at Middleboro’s local history museum.

He has his own publishing company, Recollecting Nemasket, and has published 10 books so far on the histories of Lakeville, Middleboro and other local towns.

Maddigan said history, whether it occurred in your backyard or not, is important.

“Local history should be as well documented as our national history,” he said. “It can be amateurish, but I’m trying to show it can be well done.”

Maddigan will sell and sign copies of his book on July 23 at the Onset Music Festival from noon to 6 p.m. and the Onset Blues Festival on Aug. 6 starting at 10 a.m.

“Onset and Point Independence” is available for sale online at www.arcadiapublishing.com.