Overview
Mount San Antonio, universally known as Mt. Baldy, is the highest peak in the San Gabriel Mountains at 10,069 feet and the most prominent summit visible from the Los Angeles basin. The Devil's Backbone route is the classic approach in Angeles National Forest: an exposed knife-edge ridge that connects the ski area to the summit with views dropping thousands of feet on both sides.
The full hike from Manker Flats is about 11 miles out-and-back with 3,900 feet of elevation gain. An alternative is to take the Mt. Baldy ski lift (when operating in summer, typically weekends and holidays, $25 round trip) to the top of the ski area, which cuts about 3 miles and 1,500 feet of climbing off the total. Either way, the Devil's Backbone ridge section is the highlight and the crux of the hike.
A free, self-issue wilderness permit is required. Pick one up at the kiosk at the Manker Flats Trailhead before you start.
The Route
Manker Flats to the ski area (0 to 3.5 miles). From the parking area, follow the Baldy Bowl Trail or the ski hut approach trail up through the San Antonio Ski Hut (a historic Sierra Club hut at 8,200 feet). The trail climbs steeply through mixed conifer forest on a well-worn path. The alternative is to walk the ski area fire road, which is longer but less steep.
Ski area to Devil's Backbone (3.5 to 4.5 miles). From the top of the ski area (if you took the lift, this is your starting point), the trail traverses the upper mountain toward the backbone ridge. Views begin opening up dramatically.
Devil's Backbone (4.5 to 5.5 miles). This is the signature section: a narrow ridge with steep drops on both sides. The trail is about 2 to 3 feet wide in places with exposure into the San Antonio Canyon to the north and the East Fork drainage to the south. In clear conditions, the backbone is thrilling but manageable for experienced hikers. In wind, rain, ice, or snow, it becomes genuinely dangerous. There is no protection from falls on the exposed sections.
Summit (mile 5.5). The final push from the backbone to the summit is a moderate scramble on rocky terrain. The summit is flat and spacious with a benchmark and usually a register. Views extend to the Pacific Ocean, Catalina Island, the Mojave Desert, the San Bernardino Mountains, and on very clear days, the southern Sierra Nevada. The Los Angeles basin spreads out below you, and on most days, you're literally above the smog layer.
When to Visit
May through November is the standard season. Snow can linger on the north-facing slopes and the backbone into May in heavy snow years.
October and November: The best months. Heat and haze diminish, the air is clearer, and the Santa Ana winds occasionally create crystal-clear conditions with 100+ mile visibility. Temperatures are cool and comfortable.
Summer (June through August): Hot at lower elevations but cool at the summit (50s to 70s). Start before dawn to avoid the heat on the lower trail and to ensure clear morning views. Afternoon clouds often obscure the summit by midday.
Winter and spring: Snow and ice make the Devil's Backbone extremely dangerous. The narrow ridge with ice is not a place for crampons and ice axes unless you are experienced in winter mountaineering. Multiple fatalities have occurred on the backbone in winter conditions.
What to Bring
- Water: 3 to 4 liters per person minimum. There is no water on the route. The dry heat at lower elevations and the altitude combine for aggressive dehydration.
- Layers: Summit temperatures can be 30+ degrees cooler than the trailhead. Wind on the backbone is common. Bring a warm layer and wind jacket.
- Sun protection: Exposed terrain above treeline. Sunscreen, hat, sunglasses.
- Trekking poles: Helpful on the backbone for balance and on the steep descent.
- Headlamp: Essential if starting before dawn, which is recommended in summer.
Practical Details
Parking: Manker Flats lot holds about 50 cars. An Adventure Pass ($5/day or $30/year) is required. The lot fills before dawn on summer weekends. Overflow parking exists along the road, but is limited.
Wilderness permit: Free, self-issue at the trailhead kiosk. Fill out the form and deposit it in the box before you start. This is required.
Dogs: Not recommended. The exposed backbone ridge is dangerous for dogs, and there is no water on the route.
Ski lift option: The Mt. Baldy ski lift operates on weekends and holidays in summer ($25 round trip) and eliminates the lower trail section. It's a good option if you want to focus on the backbone and summit. Check the Mt. Baldy Resort website for current operating hours.
Difficulty context: This is a serious Southern California summit hike. The distance, elevation gain, altitude, exposure on the backbone, and potential for heat all combine to make it demanding. It's not a casual outing. Hikers unfamiliar with high-altitude, exposed terrain should build up to this with shorter San Gabriel Mountain hikes first.
Getting There
From Los Angeles, take I-10 east to I-210 east, then exit at Baseline Road in Claremont. Head north on Padua Avenue, which becomes Mt. Baldy Road. Follow Mt. Baldy Road through Mt. Baldy Village to the Manker Flats Trailhead at the road's end. Total drive time from downtown LA is about 1 hour 15 minutes.
From Ontario/San Bernardino, take I-210 west to the same exit, or take I-15 south to SR-83 north, which connects to Mt. Baldy Road. About 45 minutes.
Beyond the Summit
Strong hikers sometimes combine Mt. Baldy with a traverse to West Baldy or Ontario Peak for a longer ridge walk. These extensions add significant distance and require route-finding skills, as the social trails are not officially maintained.
For a less intense San Gabriel Mountains experience, try the Icehouse Canyon Trail (7.5 miles, moderate), which climbs through a forested canyon to Icehouse Saddle with options to bag several peaks from the saddle.
Mt. Baldy is the mountain that millions of Angelenos see from their windows every day, and standing on its summit puts the entire region in perspective. The Devil's Backbone is the kind of ridge walk that stays with you: narrow, exposed, and absolutely unforgettable on a clear day. Start early, bring enough water, and check conditions before you go.