Valero Energy says it is permanently closing its Delaware oil refinery, where 550 workers will lose their jobs.
The company said Friday it must close the Delaware City refinery because of poor economic conditions.
Demand for fuel has been falling for some time and the recession has made things worse, squeezing profit margins for companies like Valero.
The company tried to sell the refinery but found no buyers.
The state says it will try to help those who are losing jobs. Valero cut 150 jobs at the refinery in September.