Personal transportation is dominated by automobiles, which operate on a network of 4 million miles of public roads,[527] including one of the world's longest highway systems at 57,000 miles.[528] The world's second largest automobile market,[529] the United States has the highest rate of per-capita vehicle ownership in the world, with 765 vehicles per 1,000 Americans.[530] About 40% of personal vehicles are vans, SUVs, or light trucks.[531] The average American adult (accounting for all drivers and non-drivers) spends 55 minutes driving every day, traveling 29 miles (47 km).[532]Mass transit accounts for 9% of total U.S. work trips.[533][534] Transport of goods by rail is extensive, though relatively low numbers of passengers (approximately 31 million annually) use intercity rail to travel, partly because of the low population density throughout much of the U.S. interior.[535][536] However, ridership on Amtrak, the national intercity passenger rail system, grew by almost 37% between 2000 and 2010.[537] Also, light rail development has increased in recent years.[538] Bicycle usage for work commutes is minimal.[539]The U.S. power transmission grid consists of about 300,000 km (190,000 mi) of lines operated by approximately 500 companies. The North American Electric Reliability Corporation (NERC) oversees all of them.The civil airline industry is entirely privately owned and has been largely deregulated since 1978, while most major airports are publicly owned.[540] The three largest airlines in the world by passengers carried are U.S.-based; American Airlines is number one after its 2013 acquisition by US Airways.[541] Of the world's 30 busiest passenger airports, 12 are in the United States, including the busiest, Hartsfield–Jackson Atlanta International Airport.[542]EnergyFurther information: Energy policy of the United StatesThe United States energy market is about 29,000 terawatt hours per year.[543] Energy consumption per capita is 7.8 tons of oil equivalent per year, the 10th highest rate in the world. In 2005, 40% of this energy came from petroleum, 23% from coal, and 22% from natural gas. The remainder was supplied by nuclear power and renewable energy sources.[544] The United States is the world's largest consumer of petroleum.[545]For decades, nuclear power has played a limited role relative to many other developed countries, in part because of public perception in the wake of a 1979 accident. In 2007, several applications for new nuclear plants were filed.[546] The United States has 27% of global coal reserves.[547] It is the world's largest producer of natural gas and crude oil.[548]Water supply and sanitation
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