Here are the statistics for inter-us shipping. Trucking is still by in large the most common way to move something across the United States. Railroads are more efficient but not as prevalent as the government would like it to be. The DOT has a ongoing campaign to shore up the railroad infrastructure in the U.S in order to make the leap from trucking to RR's.
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http://www.rita.dot.gov/bts/sites/ri...figure_03.html