Eight years ago the concept of neighborhood book exchanges made its way to Duluth. The original Little Free Library was built in Hudson, Wis., in 2009. Duluth had its first in 2012, and by 2013 there were about 20 in the city. Today there are roughly 40.

It’s a global movement. The nonprofit Little Free Library organization estimates there are now more than 100,000 registered book exchanges in more than 100 countries worldwide.

If you’re unfamiliar with these little libraries, their appearance consists of a bird-house looking box, around 20 inches by 15 inches by 18 inches, typically with a Plexiglas door. Inside is an array of books assembled for the purpose of sharing. Anyone is welcome to take a book or leave a book.

There are 38 book exchanges in Duluth cataloged on littlefreelibrary.org, and several more are in surrounding communities. If you’re interested in where to find them, visit the Little Free Library website and search “Duluth,” “Superior” or the area of your choice. The locations will pop up and you can find the one closest to you.