Disclosures from railroads about volatile oil shipments from the Northern Plains show dozens of the trains passing weekly through Illinois and the Midwest and up to 19 a week reaching Washington state on the West Coast.
The Associated Press obtained details on the shipments Tuesday under public records requests filed with state emergency officials.
Details on the shipments were turned over to states under an order from the U.S. Department of Transportation. That came after fiery accidents including an oil train derailment last July in Quebec that killed 47 people.
Railroads have sought to prevent the public disclosure of the information, citing security concerns. Some states have agreed to requests from BNSF Railway, CSX and Union Pacific to keep the information confidential. Those include California, New Jersey, Minnesota and Colorado.
But the Federal Railroad Administration determined the information is not sensitive information that must be withheld from the public to protect security.
The Bakken's light, sweet crude is more volatile than many other types of oil. It's been involved in most of the major accidents as the crude-by-rail industry rapidly expanded during the past several years. Each train can carry 3 million gallons of the fuel and the order covers all shipments of a million gallons or more.
Officials in New York, North Dakota and Wisconsin said they still were weighing whether restrictions on the information would violate state open-records laws.
U.S. crude oil shipments by rail topped a record 110,000 carloads in the first quarter of 2014. That was the highest volume ever moved by rail, spurred by the booming production of shale oil from the Northern Plains and other parts of the country, according to the Association of American Railroads.