the rail industry. Since then, U.S. freight railroads have reorganized, discontinued their lightly used routes and returned to profitability. Freight railroads Freight railroads play an important role in the U.S. economy, especially for moving imports and exports using containers, and for shipments of coal and oil. According to the British news magazine The Economist, "They are universally recognised in the industry as the best in the world." Productivity rose 172% between 1981 and 2000, while rates decreased by 55% (after accounting for inflation). Rail's share of the American freight market rose to 43%, the highest for any rich country. U.S. railroads still play a major role in the nation's freight shipping. They carried 750 billion ton-miles by 1975 which doubled to 1.5 trillion ton-miles in 2005. In the 1950s, the U.S. and Europe moved roughly the same percentage of freight by rail; by 2000, the share of U.S. rail freight was 38% while in Europe only 8% of freight traveled by rail. In 2000, while U.S. trains moved 2,390 billion ton-kilometers of freight, the 15-nation European Union moved only 304 billion ton-kilometers of freight. In terms of ton-miles, railroads annually move more than 25% of the United States' freight and connect businesses with each other across the country and with markets overseas. In 2018, US rail freight had a transport energy efficiency of 473 tons.miles per gallon of fuel. U.S. freight railroads are separated into three classes, set by the Surface Transportation Board, based on annual revenues: Class I for freight railroads with annual operating revenues above $346.8 million in 2006 dollars. In 1900, there were 132 Class I railroads. Today, as the result of mergers, bankruptcies, and major changes in the regulatory definition of "Class I", there are only seven railroads operating in the United States that meet the criteria for Class I. , U.S. freight railroads operated 139,679 route-miles (224,792 km) of standard gauge in the U.S. Although Amtrak qualifies for Class I status under the revenue criterion, it is not considered a Class I railroad because it is not a freight railroad. Class II for freight railroads with revenues between $27.8 million and $346.7 million in 2000 dollars Class III for all other freight revenues. In 2013, the U.S. moved more oil out of North Dakota by rail than by the Trans-Alaska pipeline. This trend—tenfold in two years and 40-fold in five years—is forecast to increase. Classes