The Colby Canyon Trail is located in the Angeles National Forest in the Arroyo Seco Canyon area off State Highway 2 also known as Angeles Crest Highway. The Trail is 2.181 miles long with an elevation gain of roughly 1340 feet.
The trail ends at Josephine Saddle where it intersects several other trails, Strawberry Potreo Trail, Strawberry Peak trail (CC) and old Strawberry Spur road.
The trail is part of the original route to the Colby Ranch a homestead established in 1895 by Delos and Lillian "Ma" Colby. see "The San Gabriels" chapter 16 By John W Robinson. I'm unsure if the Strawberry Potreo Trail is the original continuation of the trail to Colby Ranch or if it's a modern addition to the trail system.