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Henninger Flats Letterbox LbNA #4427

Owner:Buzzard Contact
Plant date:Jun 21, 2003
County:Los Angeles
Found by: PeterK
Last found: Jan 7, 2007
Hike distance:Unknown
Last edited:Jun 21, 2003
Distance: 5.4 miles round trip (I was personally told by Ryan that this distance is child's play, but he hikes the Appalachian Trail!)

Difficulty: Very Strenuous. This trip requires a 2.7 mile hike up the historic Mount Wilson Toll Road, and then a 2.7 mile return by the same route—no public vehicles are allowed. The toll road itself is a 12-foot wide, well-graded dirt road, but it travels very steeply up into the San Gabrial Mountains, and there is no shade until you reach Henninger Flats; because of this, you should only make this trip early in the morning, or whenever the weather is cool. This trail passes through a rugged wilderness area, so watch for rattlesnakes, wear sunscreen and a hat, and bring water. Henninger Flats is open 7 days a week, and hiking is allowed from sunrise to sunset.

Directions traveling west: Take the West 210 Freeway to Pasadena and exit on Sierra Madre Blvd./San Marino. Turn slight left onto Maple Street. Take Maple a few blocks to Altadena Drive. Turn right on North Altadena Drive for 2.7 miles to Crescent Drive. Turn right on Crescent and right again on Pinecrest Drive to find the entrance to the trail. You’ll need to park out on Crescent. Observe the parking signs carefully.

Directions traveling east: Take the East 210 Freeway to Pasadena and exit on Sierra Madre Blvd./Altadena Drive. Stay straight to go onto Corson Street for one block to Altadena Drive. Turn left onto North Altadena Drive for 2.7 miles to Crescent Drive. Turn right on Crescent and right again on Pinecrest Drive to find the entrance to the trail. You’ll need to park out on Crescent. Observe the parking signs carefully.

Henninger Flats is a pine-shaded area that has a rich history. It was originally homesteaded in 1880 by William K. Henninger who planted hay, melons, corn, and fruit trees in his “farm in the clouds.” After harvesting his crop, he would pack the produce down the steep trail he built to Eaton Canyon, and beyond to markets in Pasadena and Los Angeles. This trail later became part of the Mount Wilson Toll Road which from 1891 until 1938 was one of the few trails into the San Gabrials. In 1917, Chinese laborers widened the Toll Road to its present size to allow the passage of the 100-inch Hooker telescope on its way up to the Mount Wilson Observatory. Bottles of Japanese sake have been found along the trail that date from this time period (apparently the Chinese laborers liked Japanese sake as well as the Japanese). The Hooker Telescope was the largest telescope in the world until the 200-inch Hale Telescope was installed on Mount Palomar in 1947. Since 1928, the Flats have served as a high-elevation experimental conifer nursery for the Forest Service. 20,000 trees are grown yearly at the nursery for use in the reforestation of burned areas, soil erosion control, and roadside stabilization. Many of the early trees in Los Angeles’ Griffith Park came from seedlings grown on Henninger.

Camping, firewood, wood stoves, horse corral and flush toilets are all free of charge to the public (camping and fire permits are required, so please call (626) 794-0675 for information). There is a Visitor’s Center with exhibits and photographs showing the history of the Mount Wilson Toll Road and the local mountains. A County Forester is on duty 24 hours a day. No motorized vehicles are allowed.

SPECIAL NOTE: Please make this trip primarily to enjoy the historically rich hike, and the visit to Henninger Flats; otherwise, you may be very disappointed should you happen to find my letterbox missing after that long, hot climb.

From the entrance to the trail at Pinecrest, walk down the path and across the bridge spanning Eaton Canyon, then up the Mount Wilson Toll Road into the San Gabrial Mountains (do not descend down into Eaton Canyon, though if you check the LBNA clue listings under the city of Altadena, you’ll see there are a number of letterboxes hidden in Eaton as well). Follow the Toll Road uphill for 2.7 miles. There are markers at the one and two mile marks. At the end of the hike, you’ll come to the prominent stone and wood sign marking the entrance to Henninger Flats. To find the letterbox, stand in front of the sign, and reach your hand out to touch the name Henninger. Now take a compass reading of 20 degrees. Your compass will be pointing towards a small, dark green pine tree, sitting about 30 feet away from you, behind a short wooden fence. The letterbox is hidden under a rock at the base of the pine tree. Before going for the box, you might want to peek down the trail to make sure no one is walking up to surprise you. Please carefully re-hide the box (preferably better than I hid it), then walk around the historic Flats before filling up your water bottle and returning 2.7 miles down trail to your car.