According to CalTrans, 140,000 cubic yards of road debris are deposited on California's highways each year; 155 deaths have been attributed to accidents involving objects on highways in the state during the past two years. The big change in recent years has been the shift from "intentional" litter (e.g., fast-food trash tossed out the window) to "unintentional" litter (e.g., an entire dinette set falling off the roof of a Taurus- running on a space-saver spare tire at 90MPH, natch- after being secured there with kite string and optimism) making up the bulk of the highway trash. The huge increase in pickup-truck ownership and general do-it-yourselfism has added to the chaos. All we're gonna say is: rope is cheap.
Highway Debris, Long an Eyesore, Grows as Hazard [New York Times]
Related:
Question of the Day: What's the Worst Thing You've Done to Other Drivers? [internal]