USA. San Diego, California. 2006. Border Field State Park. At Imperial Beach on the US side of the border, the wall that separates USA from Mexico runs into the Pacific Ocean. It is made from lengths of rubber coated steel track driven into the sand. Here, children play on both sides of the wall but remain within a few feet of their parents on the Mexico side. Although there are some gaps wide enough for humans to pass, the beach is under surveillance by parked Border Patrol vehicles, sensors spotlights and helicopters. The intense surveillance has driven migrants to cross further east through the mountains and desert where many die of exposure and dehydration, are vulnerable to vipers, or may be attacked by vigilante groups such as the Minutemen on the US side. Construction began in 1994 under President Clinton's Operation Gate Keeper.