The Macon County Historical Society had its birth on May 25, 1916, when twelve people met in the Decatur Public Library, adopted a constitution, and elected temporary officers.
In August 1916 there was an appeal to members at the Old Settlers' Picnic for any items of historical interest. The Society had plans "to establish a library of local and state history, to maintain a museum, and to cultivate the historic sense and diffuse knowledge upon these subjects by meeting and publications." On more than one occasion over the years the Society became inactive and then reorganized.
In 1962 several local citizens met to discuss the reactivation of the Society, with meetings being held in Decatur's old Carnegie Library until the Society purchased the old North Cumberland Presbyterian Church to establish their new museum and a meeting place.
The current location of the Society's Museum and Prairie Village complex in the former Excelsior South School was dedicated in 1979 on the 150th anniversary of the founding of both the city of Decatur and Macon County.