BISMARCK, N.D. (AP) — Dozens of mile-long trains loaded with crude are leaving western North Dakota each week, with most shipments going through the state’s most populous county while en route to refineries across the country.

The U.S. Department of Transportation ordered railroads last month to give state officials specifics on oil train routes and volumes so emergency responders can better prepare for accidents. Transportation Secretary Anthony Foxx said a pattern of fiery accidents involving trains carrying crude from the Bakken region of North Dakota and Montana had created an “imminent hazard” to public safety.