The modern electricity-generating horizontal-axis wind turbine (now often labeled with the acronym HAWT) is an obvious descendant of the historic European windmill and the small, DC-generating wind turbines of the 1930s. The resemblance is somewhat deceptive, however, since the HAWT and its less-familiar vertical-axis cousin, the VAWT, have evolved as sophisticated products of current technology. Their high performance and reliability are the result of steady improvement in methods of aerodynamic and structural design, in new materials, and in mechanical and electrical engineering. The evolution of wind turbine technology in the United States and elsewhere since World War II is described...