Blithedale Summit Open Space Preserve/
Mount Tamalpais, Marin County Open Space District/
Marin Municipal Water District,
Marin County
In brief:
6.6 mile partial loop tours middle slopes of Mount Tamalpais above Mill Valley.

Distance, category, and difficulty:
This trailhead accesses some steep fire roads and trails, but this 6.6 mile loop hike is moderate, with about 1300 feet in elevation change. Trailhead elevation is around 230 feet. The featured hike climbs to about 1200 feet on a gradual grade, then descends back to the trailhead.

Mostly shaded at the start and end, mostly exposed in the middle.

Trail traffic:

Trail surfaces:
Dirt trails and fire roads.

Hiking time:
3 hours.

Nice year round.

Getting there:
From US 101 in Marin County, exit Tiburon Boulevard/East Blithedale. Drive west on East Blithedale about 2 miles, to the junction in downtown Mill Valley with Throckmorton. Continue straight on West Blithedale, about 1.1 miles, to roadside parking near the open space gate on the right.

Get driving or public transit directions from Transit and Trails:

GPS coordinates* for trailhead:
Latitude: 37°55'15.32"N
(* based on Google Earth data, shown as degrees, minutes, seconds)

Gas, food, and lodging:
Gas, phone, stores, and restaurants back in Mill Valley. No camping in the immediate area.

Trailhead details:
Very few spots on the sides of a narrow one-lane road, just before and after the open space gate. No parking or entrance fees. No facilities. No designated handicapped parking, and trails are not well-suited to wheelchairs. There is no direct public transportation to the trailhead, but several buses access downtown Mill Valley, and you could walk to the trailhead from there.

Most trails are multi-use, but a few are signed hiking only. Dogs are permitted on this page's featured hike: they are allowed on leash on trails; off leash under voice command on fire roads. Dog owners must have a leash for each dog. Open dawn to dusk.

The Official Story:
MCOSD's Blithedale Summit page
MCOSD 415-499-6387

Map Choices/More Information:
• Use AAA's San Francisco Bay Region map to get there.
• Download the Baltimore Canyon/Blithedale Summit pdf map from the MCOSD website.
• Trails of Mt. Tamalpais and the Marin Headlands, by Gerald Olmsted (order this map from is essential.
Mount Tam Trail Map, published by Tom Harrison Maps (order from Tom Harrison Maps). Comparable to the Olmsted map.
• Tamalpais Trails, by Barry Spitz (order this book from, has a simple but detailed map, and the book is particularly helpful if you plan on exploring the tiny paths on this side of the mountain.
• Hiking Marin by Don and Kay Martin (order this book from has a good map and descriptions of this hike.
• Open Spaces:  Lands of the Marin County Open Space District, by Barry Spitz (order this book from has some simple maps and descriptions of the MCOSD trails.
• Read more at the Mount Tamalpais and Muir Woods Railway website

View photos from this hike.

Go to Bay Area Hiker Home page

This hike through Marin County Open Space land and the Marin Municipal Water District features one of the bay area's easiest and most relaxing climbs. TrailheadThanks to the easy pitch of Old Railroad Grade, an ascent from the lowlands of Mill Valley to the slopes of Mount Tam is within reach for even beginning hikers. It's a pleasant hike all year round, but I prefer to visit in winter, when the trails cross small waterfalls, sweet-smelling blossoms dangle from manzanita shrubs, and clear weather brings long views.
      The only stress I've encountered on the southeastern slopes of Mount Tam has been finding a place to park. A handful of narrow and winding Mill Valley streets provide spectacular access to the very base of the mountain, but offer very little parking. Every time I visit the West Blithedale trailhead, I seem to snag the last available parking spot. You could begin this hike further up the mountain on Fern Canyon Road (shown but unfortunately not named on the Olmsted map), which is reached via Summit Avenue. Fern Canyon Road hosts a few legal roadside spaces, all clearly marked with white paint. Old Railroad Grade
     From the West Blithedale Trailhead fire roads climb to Blithedale Ridge, and from there you can explore the trails of the adjacent MCOSD preserves Baltimore Canyon and King Mountain. These preserves all abut Mill Valley, Corte Madera, and Larkspur neighborhoods, and you'll probably see quite a few runners and daily walkers on the trails. If you're looking for solitude, a few hiking-only paths climb the forested and chaparral-lined slopes on Mount Tam, but you're advised to take Tamalpais Trails as a guide, for Temelpa, Vic Haun, and Wheeler Trails can be difficult to find and follow from beginning to end. Many cyclists begin in downtown Mill Valley and make an out-and-back journey all the way to East Ridgecrest Boulevard (a short distance from the summit of East Peak) via Old Railroad Grade. The trip, more than 13 miles, (from the open space gate at the West Blithedale trailhead) is a bit much for most hikers, but a shorter 10 mile out-and-back trek to West Point Inn is actually not difficult because of the grade. Redwoods on the side of Old Railroad Grade
     The trail we now know as Old Railroad Grade once was part of the Mill Valley and Mount Tamalpais Scenic Railway Company. Constructed in the late 1890's, before paved roads crossed the mountain, the railway transported tourists and locals from Mill Valley to Tam's summit. Double Bowknot Junction was a transfer point where passengers could switch trains and descend to Muir Woods on Gravity Cars. The railway ceased operations in 1930, a victim of the depression and increased auto traffic. No rail segments remain on the trails, but the cement transfer platform still sits near Double Bowknot, and there are plans for a Gravity Car Barn and interpretive site managed by Friends of Mount Tam at Tam's East Peak.
     Start at the open space gate at the West Blithedale Trailhead. Wide multi-use Old Railroad Grade begins an easy ascent through a forest of redwood, tanoak, and California bay. Fern Canyon Road A few clusters of big-leaf maple are pretty in autumn, but by winter all their colorful leaves are plastered to the ground by rainstorms. Seasonal streams flow downhill from Blithedale Ridge, emptying into Corte Madera Creek, and the trail follows along, heading into Blithedale Canyon. At 0.11 mile, H-Line Fire Road departs to the right at an unsigned junction. Continue straight on Old Railroad Grade.
      A few houses are still visible on the left side of the trail, but most of the sights and sounds of Mill Valley are blocked by tall trees and rushing water. Look for huckleberry, hazelnut, toyon, monkeyflower, and madrone on the sides of the trail. At 0.59 mile, Old Railroad Grade makes a sharp turn to the left, and unsigned Horseshoe Fire Road heads uphill on the right. Continue on Old Railroad Grade, which makes a transition into Marin Municipal Water District lands.
      The climb remains steady and easy as the trail ascends up out of the canyon into a mixture of plants, most prominently Douglas fir, chinquapin, Double bowknotCalifornia coffeeberry, manzanita, chamise, coast live oak, California bay, madrone, coyote brush, and toyon. Look for pink flowers on chaparral pea shrubs in late spring. Some small redwood groves nestle in the creases of the hillside, where small seasonal streams develop into winter cataracts. Jaw-dropping views stretch uphill to Tam's East Peak, and south past Mill Valley to the Marin Headlands and San Francisco Bay. At 1.87 miles, Old Railroad Grade reaches a gate. A few steps later, the trail shifts to patches of pavement: Summit Avenue. Although there are houses and driveways to the left, you might still feel you're on a trail, until, at 1.96 miles, where you'll arrive at a signed street junction and solid pavement. Turn right onto Fern Canyon Road.
      Views south are awesome along this narrow paved road. A few pricey houses perch on the hillside to the left, but on the right there's nothing but an uninterrupted carpet of chaparral sweeping uphill toward Tam's summit. At 2.20 miles, unnamed but signed Temelpa Trail heads into a dense thicket on the right. Continue on Fern Canyon Road.Hoo-Koo-E-Koo Fire Road  If you can tear your gaze away from the views, you might notice large hand-painted letters spelling out "Go Away" on the pavement. At 2.62 miles, the road ends and once past a gate you'll be back on dirt and Old Railroad Grade. There's one last house on the left, and then civilization fades again, replaced by oaks, manzanita, chinquapin, chamise, madrone, and Douglas fir on the sides of the trail. It doesn't seem possible, but the views just keep getting better and better as you ascend. On a clear day, you should be able to see Mount Diablo and the Richmond-San Rafael Bridge to the east, the Bay Bridge, Golden Gate Bridge, and downtown San Francisco to the south, and the ocean to the west. Old Railroad Grade snakes uphill, reaching an unsigned but obvious junction at 2.97 miles. This is the start of the double bowknot. Turn right, and after a few feet, at 3.00 miles, you'll arrive at another junction, this one signed. Gravity Car Grade descends, left, to the Mountain Home Inn, but turn right and remain on Old Railroad Grade.One of the spectaculr views from Hoo-Koo-E-Koo Trail
     Several clusters of pine loom over the trail. The paved platform, where passengers boarded trains, remains on the left. Old Railroad Grade curves left and passes a few coulter pines, with conspicuous cones the size and shape of pineapples. Manzanitas thrive on the sides of the trail, and you might see blossoms on these shrubs beginning in mid-December. At 3.33 miles, you'll reach a signed junction. Turn right onto Hoo-Koo-E-Koo Fire Road.
     The wide multi-use trail begins a slight descent. Chinquapin, huckleberry, manzanita, chaparral pea, chamise, shrubby oaks, and golden fleece occupy the sunny chaparral, with redwood, California bay, madrone, and ferns common along the more damp areas of the trail. Old Railroad Grade is occasionally visible downhillto the right, and you'll recross the same seasonal creeks (just at a higher elevation) as you angle across the hillside, uphill from the old train route. At 3.74 miles, you'll meet up with Temelpa Trail again, as the old path crosses the fire road at a signed junction. Continue on Hoo-Koo-E-Koo Fire Road.Hoo-Koo-E-Koo Trail
     Hoo-Koo-E-Koo Fire Road continues to descend at an easy pace. Blithedale Ridge can be easily be picked out of the landscape, looming just to the east. At 4.02 miles, another old steep footpath, Wheeler Trail, heads uphill to the left at a signed junction. Continue straight on Hoo-Koo-E-Koo Fire Road.
     No trails cross the fire road for almost a mile, but time passes quickly as Hoo-Koo-E-Koo Fire Road winds downhill through chaparral and trees. At 4.93 miles, you'll reach a signed junction with Corte Madera Trail. Turn right and steeply descend a few feet on an eroded path to a second signed junction, this one with Hoo-Koo-E-Koo Trail. Turn left. (Corte Madera Trail is a reasonable shortcut back to Old Railroad Grade, but the steep hiking-only path can be a challenge in winter, as it crosses a full creek several times, and the trail is prone to storm damage.)Blithedale Ridge Fire Road
     After miles on fire roads, it's an adjustment to walk on narrow hiking-only Hoo-Koo-E-Koo Trail. Watch your footing in wet weather, as exposed roots and rocks can be slippery. Initially the trail descends easily through a forest of redwood and California bay, but Hoo-Koo-E-Koo Trail gradually emerges out of the canyon into a mixture of chaparral and trees. Look for sagebrush, chinquapin, toyon, coyote brush, madrone, tanoak, huckleberry, silk-tassel, manzanita, chamise, and oaks. The trail crosses an open hillside just below Echo Rock, where you might see tiny waterfalls after winter rains. At a mostly level grade, Hoo-Koo-E-Koo continues back to MCSOD property and an undersigned junction at 5.40 miles. Turn right onto Blithedale Ridge Fire Road.
      The multi-use fire road traverses the length of Blithedale Ridge, with many steep dips along the way. This segment is an uncommonly focused downhill, with madrone and oaks lining the trail, but chaparral just beyond. There are excellent views east to San Pedro Mountain, San Quentin, and the bay. At 5.67 miles, just before an uphill stretch, unsigned Horseshoe Fire Road departs to the right. Turn right.Returning on Old Railroad Grade  (You could instead continue on Blithedale Ridge Fire Road to H-Line Fire Road, and descend back to Old Railroad Grade from there. This option confronts you with a short but steep climb on Blithedale Ridge Fire Road, somewhat unwelcome at the end of a hike.)
     Horseshoe Fire Road, open to hikers, cyclists, and equestrians, descends sharply. You'll have one last view to Echo Rock and Tam's summit as you head downhill through madrone, oaks, and California bay. At 5.86 miles, a signed post marks a junction with Corte Madera Trail on the right. Continue straight on the fire road. You'll be firmly back under tree cover now, and at 6.00 miles Horseshoe Fire Road ends at a previously encountered junction with Old Railroad Grade. Turn left and retrace your steps back to the trailhead.

Total distance: 6.59 miles
Last hiked: Friday, December 14, 2001