The St. Vrain Historical Society was incorporated in 1967, after functioning for many years on a less formal basis. The upcoming centennial of the Chicago-Colorado Colony founding of Longmont in 1971 prompted much and the first activities of the Society included: a publication of "They Came to Stay", a Grand Ball at the Dickens Opera House, creation of a walking tour brochure to highlight some of the pre-1900 homes in the original Chicago-Colorado Colony, and establish the Landmark Commission.
In 1969/1970, SVHS created Old Mill Park from "blighted" land that was formally the site of the old Longmont (Denio) Flour Mill that burned in the 1930s, transforming it into a historic "mini park". Today, the park now serves as a "sanctuary" to many old pioneer era buildings related to Longmont and Boulder County's history: The Affolter Cabin (1860), The Hauck Milk House (1860), The Billings Cabin (1890). In addition, the park also holds other structures related to Longmont's past like the Gildner Gazebo (1916), and the antique street lamps that were once part of Old Main Street. SVHS formally dedicated Old Mill Park on August 1, 1976 in conjunction with Colorado's Centennial and the National Bicentennial.
In 1976, SVHS spearheaded a five-year community-wide effort to rescue Longmont's oldest standing church; "Old" St. Stephen's (1881) saving it from destruction and later helping place it on the National Register of Historic Places.
In the early 1990s SVHS then purchased the original farmhouse once belonging to the 160-acre farm established by Charles Hover in 1902. The other Farmstead buildings were acquired in 1996. When the barn became victim to arson fire the society then reconstructed the barn to what was once their originally.
Finally, in 1997 the Society acquired the 1913-1914 English Tudor, Gothic Revival, Hover Mansion, known as "Hoverhome" owned by Charles L. Hover, a notable Longmont resident and Colorado Citizen. This house contains many of the original furnishings belonging to the Hover family and is used for historic tours and programming as well as an event space.
Today, SVHS intends to continue operating these four beloved local historic landmarks for public benefit and education.