Overall CO2 emissions fell by 13 percent over the past five years as new energy-saving technologies were adopted, including a switch from coal to wind, solar and cleaner-burning natural gas.
Geothermal and hydroelectric sources also helped reduce air pollution.
But America got 31 percent of its energy from natural gas, which came about due to an explosive use of fracking.
Environmental organizations say the shattering of the bedrock to help in the extraction of natural gas has come with its own cost to the environment.
Overall energy use in the U.S. has fallen 6.4 percent since 2007. This has mainly been due to more efficient heating and cooling systems and better fuel economy in vehicles.
America’s improvement in greenhouse gas emissions is offset by the burst in air pollution being generated in developing countries such as China.