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It was shut down earlier this moth for unscheduled repairs. At the time, prices were on average $2.38, but some prices spiked in the Great Lakes region.

With the restart, Patrick DeHaan, of GasBuddy.com, said that in the next few weeks we could see prices drop quickly from 20 to 50 cents a gallon.

DeHaan told AP that he expects to see prices drop below $2 a gallon, especially in Michigan, Illinois and Ohio.

The refinery restart comes as oil has been trading at its lowest cost in years, hovering just under $40 a barrel.