PORTLAND – Lucy Oster was riding her bike to the public library — a trip that the 12-year-old often makes twice a week — when she noticed a tiny new building on her route.

It was a roughly 2-foot-high structure with a shingled roof, sitting atop a post and located in the front yard of a house in Deering Center. Inside were crammed 20 to 30 books.

On the edge of the roof was a little wooden sign that read, “Little Free Library.”

Lucy had never heard of a Little Free Library before, but she instantly loved it. She took a book from the “Charlie Bone” series and rode happily off.

Little Free Libraries have been popping up on front lawns around Maine recently like giant book-filled flowers. The phenomenon began in Wisconsin about three years ago and is gaining thousands of devotees worldwide for its simple idea and lofty mission: Ask people to take a book and leave a book, and in the process build stronger communities, foster better relationships among neighbors and promote a love of reading.

“I saw the sign and thought it was so cool,” said Lucy, who was on her way to the Burbank Branch of the Portland Public Library when she discovered her neighborhood’s book shack. “I mean, it’s a little free library. I’m a big library fan.”

Besides Deering Center, you can find these mini-literary trading posts in Falmouth, Cape Elizabeth, Saco and in at least three spots in Portland’s East End. They are all over the state, as far north as Presque Isle.

In May, the Curtis Memorial Library in Brunswick collaborated with Hammond Lumber, Lowe’s and local high school students on a project to help more than a dozen groups build their own Little Free Libraries and install them around the midcoast.

“When it comes to our mission, the sense of community trumps everything,” said Rick Brooks, a retired educator from Madison, Wis., who three years ago helped found the nonprofit group Little Free Library Ltd. “It’s about sharing something you value and doing something nice for your neighbors. And you never know what books people will find.”

The idea began with Brooks’ friend Todd Bol, who built the first Little Free Library in 2009 as a tribute to his mother, a former teacher. He made it look like a little schoolhouse on a post, filled it with books, and asked people to take and leave books. The next year, other people started building them as well.

The idea has caught on in such a big way that there are an estimated 10,000 Little Free Library sites around the world, said Brooks. He doesn’t know for sure, because the organization’s small staff can’t keep up with the job of listing all the registered sites on a map on the group’s website, littlefreelibrary.org.

People pay $35 to register their Little Free Library, which gets them on the map (eventually), an official “Little Free Library” sign and lots of resource material.

The registration fee also gets Little Free Library “stewards” access to book labels and plates, and “how-to” information that deals with where to locate your library (on a busy pedestrian route, preferably), how to run a book swap, and related topics.

There is also a section on the website where people can buy library structures for around $150 and up if they don’t want to build their own. Brooks says people can build any kind of structure they want — there’s no particular style or pattern to follow.

“People have made some really well-crafted ones, and some people make them out of old beehives, microwave ovens — all sorts of things,” said Brooks. “It’s fun for people to travel around and see all the different ones.”

The main reason for a registration fee, Brooks said, is to help the group spread the Little Free Library idea and provide structures to people who can’t buy or build their own.

The Little Free Library that Oster found on her bike ride was installed around Memorial Day on the front lawn of Kristin Jordan, at Lawn Avenue and Concord Street.

Jordan, a mother of three between the ages of 3 to 6, read an article last year about the national movement.

“I’m a bookworm, and when I read about it, I just became smitten,” Jordan said.

Jordan registered her Little Free Library, but it was built by her husband, Tom, a window salesman, from materials they had left over from home remodeling.

As soon as it went up on the corner of the Jordans’ property, the Little Free Library started getting used. People see the sign, read the information that details the “Take a book, leave a book” ethic, and jump right in.

“I’ve got about 40 books in there, and we see new books in there every single day,” said Jordan, 36. “I have three children, and it’s so exciting for them to run out to see what’s out there.”

Julie Falatko of South Portland installed her Little Free Library about a year ago in front of her home on Reynolds Street. Falatko’s husband built it out of home renovation leftovers. The little structure looks like a miniature version of their house.

Falatko has enjoyed watching people discover the library with a sense of wonder and joy.

She’s seen people walking their dogs at midnight perusing the selection. And she’s seen a boy who said he didn’t like to read find a book that he was actually excited to get his hands on.

“It’s really fun to watch people’s reactions,” she said.

Like other local Little Free Library stewards, Falatko said it’s not hard to stock the library — she just uses her own books and keeps an eye out for material at yard sales and book sales.

So far, users have been very good about putting a book in when they take a book out at the Little Free Libraries.

“I started it up with about 20 books, and there are always about 20 books in there,” said Jon Woodcock of Blake Avenue in Saco, who built a Little Free Library with his son Noah about a year and a half ago. “We keep novels and things for adults on top; kids’ books on the bottom.”

Woodcock said he and Noah built their library out of some old pallets and other materials around the house.

The only material he had to buy was a piece of transparent hard plastic to use as the see-through door to the little roofed box.

Little Free Libraries seem to be fairly free of vandalism, and Woodcock said he has had no problems.

“I see the police patrolling in our neighborhood, and I know they keep an eye on it,” he said.

Local library administrators are keeping an eye on the Little Free Library trend, too. Some are getting directly involved, like the staff at Curtis Memorial Library in Brunswick, where programs have been held to build them.

Even library officials who haven’t yet dabbled in the Little Free Library arena appreciate what it can do for books and libraries in a big-picture sense.

“It’s a nice extension (of the library concept), sort of like branches at the neighborhood level,” said Kevin Davis, director of the South Portland Public Library.

“It puts a thought in people’s heads, it helps people get into the library habit.”

Jordan likes the fact that the library is helping her share “the love of reading and books” with her three children.

She also loves the idea that her Little Free Library has created a neighborhood focal point and gathering spot where there previously had been none.

Sort of like a water cooler, but with books.

“I’ve seen people stop, take out a book and say, ‘Look at this one,’” said Jordan. “We’ve met so many people through this.”

Ray Routhier can be contacted at 791-6454 or at:

rrouthier@pressherald.com