A total of 5,116 megawatts of wind power was built in 2010, about half the level the industry added in 2009, as weak electricity prices and the global economic slowdown weighed on the industry, according to the American Wind Energy Association.
That dropped the United States behind China in total installed capacity, as China added 18,900 MW to become the global leader with nearly 45,000 MW of installed capacity.
The United States has about 40,000 MW of capacity, enough to power more than 10 million homes, according to AWEA.
Texas remains the biggest contributor, with about one-fourth the total. That total represents about 2 percent of the U.S. power supply.
Wind power still contributed more than a quarter of the total new electricity supply in the country.
About half the turbines installed in the U.S. market last year were supplied by General Electric Co, followed by Siemens AG, Gamesa, Mitsubishi Corp, Suzlon Energy and Vestas Wind Systems.
Natural gas-fired power plants were the largest new source of power to be built in the country, making up about 40 percent of new additions, followed by coal and wind power.
Wind has totaled about 35 percent of total U.S. power plant additions since 2007, according to Denise Bode, chief executive of AWEA.
The industry's downturn has made it more efficient, she told reporters, enabling it to cut costs dramatically.
"All the fat's out," she said, adding that in many regions of the country it is cheaper to add wind turbines than to build advanced natural gas-burning plants.
The cost cuts have made it possible to sign power sales agreements at 5 to 6 cents per kilowatt hour in some places in the Midwest, according to AWEA data.
That price is nearly on a par with electricity generated by coal plants there.
Still, the downturn has left the industry, which employs about 75,000 people, with an overcapacity.
"We have the capacity to add 13,000 megawatts next year," she said.
As of the beginning of 2011, an estimated 5,600 MW of new wind generation was under construction.