In 2005, Regional Parks joined together with several public agency partners to realize the vision of a 4.5 mile trail connection between Jack London State Historic Park and the trailhead at the North Sonoma Mountain Park & Preserve.
Through a series of land acquisitions and easements, the properties were assembled together as the basis for the Park & Preserve. An Initial Study and Mitigated Negative Declaration for the North Sonoma Mountain Ridge Trail Project, entry road, and staging area was approved by the Sonoma County Agricultural Preservation and Open Space District Board of Directors in March 2008, in compliance with the California Environmental Quality Act (CEQA).
In the summer of 2014, four Sonoma County Agricultural Preservation & Open Space District properties were transferred to Regional Parks. Construction of a new 4.5-mile multi-use trail and trailhead parking area was completed in December of 2014.
The North Sonoma Mountain Regional Park & Open Space Preserve was opened to the public on Valentine's Day, 2015.