Puente Hills, near Whittier, was the main landfill for much of Los Angeles County, and the largest active landfill in the nation, until it closed in 2013, after 56 years of operations (though it still accepts clean dirt). The landfill has filled in a canyon on the edge of the mountains, and expanded outward. The Material Recovery Facility there is still open, and is among the largest MRF in the nation. It is also the depot for the proposed trash train, which would connect to the Mesquite Megafill dump site 150 miles away, near the Salton Sea.
