It is located at 18 Maine Street, in a handsome brick Federal style building that served as the U.S. Customhouse from 1815 until 1913.

Its front facade, facing west, is five bays wide, with windows set in segmented-arch openings, and the entrance located asymmetrically in the second bay from the left, in a round-arch opening with a half-round transom.

The second floor was taken up by the local customs offices, whose jurisdiction covered the ports of Kennebunkport, Kennebunk and Wells.

[2] The Kennebunkport Library Association was formed in 1916, and rented space in the building that same year.

In 2017, 5,500 square feet was added to include a business center, book sale, kitchen, community room, and an elevator.