^aData source and exclusion criteria for U.S. wind potential map coverage provided on March 16, 2006, by National Renewable Energy Laboratory, Golden, CO.

^bYrSource: Yr = Year validated (1987 to present); Source = PNL, NREL, or N/TWS (NREL with AWS TrueWind).

NOTE: PNL data resolution is 1/4 degree of latitude by 1/3 degree of longitude; each cell has a terrain exposure percent (5% for ridgecrest to 90% for plains) to define base resource area in each cell. Ridgecrest areas have 10% of the area assigned to the next higher power class. NREL data were generated with the WRAMS model and do not account for surface roughness. Resolution is 1 km. Texas includes the Texas mesas study area updated by NREL using WRAMS. N/TWS data was generated by AWS TrueWind and validated by NREL. Resolution is 400 m for the northwest states (WA, OR, ID, MT, and WY) and 200 m everywhere else. These data consider surface roughness in their estimates.