On October 10, 2014, President Barack Obama used his authority under the Antiquities Act to create the new monument, protecting 346,177 acres of public lands in the San Gabriel Mountains of the Transverse Ranges.

[2] The movement to further preserve the San Gabriel Mountains began in 2003 when then Congresswoman Hilda Solis initiated an environmental feasibility report to see if it was possible to increase protection by National Monument designation.

[4] The creation of the monument was in response to decades of input and support from the local community demanding greater environmental protections for the heavily touristed region.

[5] The Obama administration cited the presence of endangered species, important cultural resources, and the threat of unreliable funding for management and encroaching development as the proximal reasons for the establishment of the monument.

[6] Local officials, including Los Angeles Mayor Eric Garcetti, cheered the news along with Hispanic, recreation, and conservation groups.