San Gabriel National Forest was established as the San Gabriel Forest Reserve (or San Gabriel Timberland Reserve) by the United States General Land Office in California on December 20, 1892 through a proclamation order by President Benjamin Harrison. With and area of 555,520 acres (2,248.1 km2) (extending from Pacoima Canyon at Sylmar to Cajon Pass in Southern California),[1] it was the first federal reserve in the state of California.
After the transfer of federal forests to the U.S. Forest Service in 1905, it became a National Forest on March 4, 1907.
On July 1, 1908 part of the forest was combined with Angeles National Forest and the remainder with Santa Barbara National Forest, and the name was discontinued.[2]