The Backbone Trail is a wide gravel trail that traverses the majority length of the Lehigh Portland Trails property. The trail is about 11 feet wide, and is surfaced with fine limestone screenings. The surface is smooth and fast, and handles rain well. Even when the singletrack is muddy, the gravel trails can still be ridden.

The Backbone connects the Eastern Trailhead to the Western Trailhead, and passes through a variety of terrain, from densely-packed cedars, to hardwood forest, to riparian woodlands, to flat grassy stretches along Elm Creek. There is a lot of nice scenery along this trail, including expansive views of both Lake Lehigh and Elm Creek. Part of the path runs atop on old railroad line, the Missouri Pacific, which serviced the Lehigh Portland Cement plant back in the day.

Most of the other trails in the network branch off from the Backbone, including the East Loop Trail, the West Spur Trail, Creekside, Mt. Lehigh, the South Loop, the Mountain Goats, and Lakeside West. At the western trailhead, it connects to the Connector Trail leading to the Southwind Rail Trail through Elm Creek Park South.

The Backbone Trail is a great trail for families, walkers, those with limited mobility, and bicyclists lacking mountain bikes suitable for the singletrack trails. There are a couple of nice downhills headed west (and the corresponding uphills headed east).