The Union County Historical Society found its origins in the late nineteenth century with the formation of such organizations as the Union County Pioneer Association in 1875 and the Agassiz Scientific, Archœlogical and Historical Society in 1879. The current organization, the Union County Historical Society, was founded in 1949. In 1954, Lieutenant Colonel Dana Woods Morey (1876-1953) bequeathed his 1891 Queen Ann style brick home located at 246 West Sixth Street in Marysville to the Society for use as a museum. The Morey family was prominent furniture makers and undertakers in the community from the mid nineteenth century to early twentieth century.

The museum has been restored to its original condition when the Morey family resided in it in the early twentieth century, including original gas light fixtures, cobalt-blue stained-glass windows, parquet floors, hand-milled oak and burled-maple woodwork, carved mantelpieces, decorated porcelain sinks and a zinc bathtub fed by gravity cistern tanks located in the attic. An annex was constructed in 1965 to supplement and display the larger items of the museum's collection. The front door of the annex is a replica of the door from the Union County boyhood home of Vice-President of the United States Charles W. Fairbanks.  The original door is on display in the museum.

The museum contains many items relating to the history of Union County, Ohio. Some of the collection includes prehistoric artifacts from Union County's Native American heritage, the 1905 Brennan Automobile, being the first automobile built in Union County and one of the first automobile's built in the state of Ohio, military collection, antique toy collection, the bell from Union County's third courthouse, 1838-1883, one of the largest collections of items relating to Vice-President Charles W. Fairbanks, born in Union County and Vice-President in the Theodore Roosevelt administration, memorabilia from "Colonel" Noah Orr, the "Union County Giant," who stood nine feet tall in costume and weighed over a quarter ton and who performed in various shows, circuses and museums throughout the United States and Canada, and many other displays of local significance.

Mission

The Union County Historical Society is the county organization responsible for the collection and preservation of objects relating to the history of Union County, Ohio. The Society actively and energetically collects items of local interest and uses them to educate and foster knowledge of Union County history in the community and continues to the present day to strive to collect and preserve the history of Union County, Ohio.