The Adams County Historical Society was formed in September 1957 to preserve and educate the history of Adams County Indiana. The original meetings were held at the local Decatur Public Library.

In February 1968 the Society purchased at auction the former Charles Dugan Mansion at 420 W. Monroe St. Decatur for the use of a home for the society and a museum for the ever growing collection of county artifacts the society had been collecting.

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