Rail transit of coal dropped by almost 11 percent in 2012, reflecting a decline in the use of coal for domestic electricity generation.
But the record increase in U.S. crude oil production prompted a dramatic rise in the use of rail to move oil and other petroleum products, according to the U.S. Energy Information Administration.
The report found crude oil and other petroleum products accounted for the biggest increase in railcar loadings among commodities in 2012, up 46.3 percent from the previous year, to 171,000 carloads.
Coal remained the dominant category, however, making up 41 percent of all commodity carloads shipped by rail.
Typically, about 90 percent of crude oil is transported by pipeline in the United States. But with a shortage of pipelines in booming U.S. shale production regions, many producers are using rail to transport crude oil to refineries and other destinations.
More than 70 percent of coal burned by power plants for electricity generation is delivered by rail, but deliveries fell in 2012 as power generators turned to natural gas.