For most states, wind speed information can be found at www.eere.energy.gov/windandhydro/windpoweringamerica/wind_maps.asp.
The maps dont account for variations due to altitude, tree lines and ground-level brush. While its possible to measure a propertys winds more precisely with an anemometer, most wind-turbine dealers dont require that level of precision to recommend a turbine size.
At awea.org/smallwind, the American Wind Energy Association has guides to selecting and installing turbines, and lists of manufacturers and state incentives. The New York State Energy Research and Development Authority lists rebate amounts and eligible wind installers at www.powernaturally.org. Information for New Jersey residents is available at njcleanenergy.com.
A national list can be found at dsireusa.org.