Black Star Canyon is a remote mountain canyon in the Santa Ana Mountains, located in eastern Orange County, California. It is a watershed of the Santa Ana River. Black Star Canyon is a popular destination for mountain bikers due to its wild scenery and the fact that its main access road is closed to automobile traffic.
Traces of the Black Star mining operation can still be found, including rusted mining equipment, abandoned shafts, and piles of low-grade coal scattered about the floor of the canyon (similar to those found in Fremont Canyon to the north). In the early 1920s, the United States Forest Service built a narrow but well-graded road up Black Star Canyon and down the eastern slope of the mountains to Corona, thus opening the ranchlands of the upper canyon to hikers.