The 2015 fourth quarter was the second best ever for American wind. In 2015 a total of 8,598 megawatts (MW) of new wind capacity was installed - this is the fourth highest annual total ever. Total installed wind capacity rose to 74,472 MW or, approximately, 48,000 wind turbines (the US DOE's 'Wind Technologies Market Report' has information on average turbine sizes).
Since 2006 US installed wind capacity has expanded by 542 percent but it will grow much more in the next five years. In December 2015, and after years of stop-go tax changes, the Production Tax Credit (PTC) was extended for five years. With this much-needed policy certainty the US now has an extremely favorable business environment and industry has already responded in spades - as noted above 4Q 2015 saw near-record installations.