Railroad records show more than a dozen volatile oil train shipments traverse Montana weekly en route to out-of-state refineries.
The information was released Wednesday by state officials in response to a request from The Associated Press.
BNSF Railway had submitted the information to the state under an order from the U.S. Department of Transportation following several explosive oil train derailments in the U.S. and Canada.
The railroad is the primary crude oil-by-rail carrier in the western U.S.
Its disclosure documents show oil trains have passed through at least 30 of Montana's 56 counties. Roosevelt County topped the list, with 20 trains in a single week.
BNSF asked Montana officials not to publicly disclose the information. Gov. Steve Bullock's office refused, citing the state's open records law.