Guardian: ‘This region needs the Mississippi’: the US government declares the incident ‘a spill of national significance’ Link to this video Britain’s biggest oil company was tonight facing an environmental disaster expected to cost more than the Exxon Valdez tanker spill as thousands of tonnes of floating oil began to reach the US Gulf coast. As several coastal states declared a state of emergency and dispatched clean-up crews, BP was desperately trying to stem not just the flow of …