Hikes #57, 57-2 and 58 in the San Gabriel Mountains
Chilao to Horse Flats, Mt. Hillyer

The date of the described hike is given in parentheses for each link.

There are two major variants of hike #57:

  1. 57: Robinson's described hike goes from Chilao to the south end of Horse Flats Campground, then to Mt. Hillyer via the Mt. Hillyer Trail, and then back along the same route. This hike is ~5.6 miles, with ~1220' elevation gain.

  2. 57-2: Schad's loop version, which Robinson gives as an alternate, goes from Chilao to Mt. Hillyer as in the first version, but then continues north from Mt. Hillyer to the Santa Clara Divide Road (3N17), east to the Horse Flats Access Road to the Campground, south to the Campground and then back to Chilao. This hike is ~5.8 miles, with ~1130' elevation gain.

The elevation gains given above were taken from reading the topo map myself, using the elevations in the table below. The mileages are taken from Schad for #2, and approximated for #1 using Schad's mileage for #2, corrected by the difference in mileages for the two options from my measurements from Topo!. See below the table for how I obtained my number.

Hike #58 is a subset of this hike, going from the Santa Clara Divide Road (3N17) to Mt. Hillyer, which is 2.5 miles roundtrip, with ~400' elevation gain.

Note that Robinson says his described hike (#1) is 6 miles roundtrip with 1000' elevation gain, and the loop hike (#2) is "an additional 2 miles". Schad says the loop hike (#2) is 5.8 miles with 1100' elevation gain. A rough measurement with Topo! (which probably gives a significant underestimate for the mileage for the trail portion) gives a mileage of 4.46 miles for #1 and 4.93 miles for #2, so the "additional 2 miles" is almost certainly incorrect.

Dan Simpson's Mount Hillyer (6162') Via Horse Flat page (09Aug03)

Sam Hartsfield's Chilao to Horse Flats and Mt. Hillyer via Silver Moccasin Trail (30Sep00)

Angeles National Forest Service's Chilao to Mt. Hillyer via Horse Flats (??)

Afoot and Afield in Los Angeles County, Schad, 2nd edition, September 2000 (1st printing), Area A-7, Trip 4, Mount Hillyer, p. 230. (< 2000)

Trails of the Angeles, John W. Robinson, Seventh Edition, September 1998, #58, Chilao to Horse Flats, Mt. Hillyer, p. 116. (< 1998)
This is Robinson's Hike #57 in previous editions.

See also #57-1, Chilao Loop via Silver Moccasin Trail and "Newcomb's" Ridge.

Altitudes for points along the hike, with total gain and loss between points

Chilao to South Horse Flats Campground
5635 45
South Horse Flats Campground to Mt. Hillyer
5630 10
6180 30
6150 50
Mt. Hillyer to Santa Clara Divide Road to South Horse Flats Campground
5640 522
Total over entire hike
Total #112221222
Total #211321132

Total for #1 consists of 475 + 612 + 90 + 45 = 1222'.
Total for #2 consists of 475 + 612 + 45 = 1132'.

To obtain the mileage for #1, I started with my rough measurements using Topo!. For #2, the road segment is 1.55 miles, which is nearly always accurately measured using Topo!. Hence assuming Schad is correct, which he usually is, the trail portion of #2 is then 5.8 - 1.55 = 4.25 miles. My Topo! measurement of 3.38 miles thus needs to be multiplied by 1.26 to get Schad's answer. Hence I applied the same factor of 1.26 to the measurements for #1, which is all trail, giving 1.26 * 4.46 = 5.6 miles.

An accurate measurement using Topo! alone is not possible because the Mt. Hillyer trail is not shown on the topo map.

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Copyright © 2000-2003 by Tom Chester.
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Updated 17 August 2003.