The John L. Lewis Building was constructed in three phases, beginning in 1976 and concluding in 1992. The first (center) section was designed to honor Lucas County's rich coal mining heritage as well as to provide galleries for general display. It was named for John L. Lewis, a native son of Lucas, president of the United Mine Workers of America and a giant in the American labor movement.
The Building Trades Class of the Chariton Community School helped frame this two-level 30- by 60-foot structure. A Bicentennial Matching Fund grant was awarded and gifts from the Lucas County Conservation Board and generous individual donors allowed the $32,000 structure to be dedicated debt free on July 4, 1976. A library on the main floor of the building was named to honor Irene Garton, founding curator, who served from 1966 until 1970.
Today, this wing contains a large general display gallery, the John L. Lewis display and the library on its upper level; a mining display and various business- and home-related displays on the lower level.
In 1981, a 30- by 60-foot lean-to addition was added to the west side of the building to house agricultural equipment and displays. In 2005 a bequest from the Swanson estate allowed this wing to be insulated and finished in a manner more suitable for displays. It continues to be used for agricultural as well as automotive displays.
The east wing of the Lewis Building was completed in 1992. Kenneth Crist headed a fund drive to raise money to build the two-level addition. This building wing now houses the Perkins room, which includes the main museum entrance, the administration office, a large commons area and several displays, on its upper level. The 20th Century Christ Gallery is located on the lower level of this wing.