In 1892 voters in Mason City approved a tax levy to establish a free public library.

The architects wanted the Bedford stone because it could be worked to a smooth finish, while the native limestone could not.

The city received a grant from the Public Works Administration (PWA) to expand the building.

The Denison Room, which overlooks the garden and Willow Creek, and an adjacent patio was completed in 1961.

The Mason City Community Theatre leased the wing from 1981 to 1997 after the Extension Service no longer used it.