DALLAS -- Tropical Storm Harvey is sending pump prices higher for U.S. motorists and causing temporary shifts in the flow of oil and gasoline around the world after taking down a huge chunk of U.S. refining capacity.

It will be days or even weeks before the energy sector in the southeast Texas Gulf Coast is back to normal operations. The region accounts for about 3 per cent of the U.S. economy and is a crucial export market for oil and chemicals.

Damage estimates are soaring, and economists say the storm and flooding could knock a fraction of a point off national economic growth in the third quarter.

Wednesday brought news that the nation's biggest refinery had begun a complete shutdown, the latest domino to fall among Gulf Coast refineries.