Construction on the backbone trail began in the early 1980s. It involved the cooperation of the
National Park Service, the
California Department of Parks and Recreation, and private parties interested in connecting existing trails within the Santa Monica Mountains NRA into a single trail spanning the length of the park. The range of conditions found on the trail - ranging from flat, wide fire roads to narrow single-track trails - reflects the trail's origin as a series of unconnected paths and backcountry roads, connected to form the Backbone Trail System. In 2016, the National Park Service completed land acquisitions from former California Governor Arnold Schwarzenegger and fitness pioneer Betty Weider to enable right-of-way for the trail. In May 2016, a new section of the trail was completed on the east side of Yerba Buena Road in support of these acquisitions. Upon its 2016 opening, the Backbone Trail was designated a
National Recreation Trail. The official opening ceremony for the Backbone Trail was held on Saturday, June 4, 2016, at Will Rogers State Park, with a ribbon-cutting ceremony held at 10:00 am. Portions of the trail were closed after the
Woolsey Fire in 2018. Other trails and several parks were closed as 88% of the federal parkland within the Santa Monica Mountains burned in the fast-moving fire. The Backbone Trail fully reopened in July 2019. == Topography and geography ==