The International Clean Energy Analysis (ICEA) gateway estimates that the U.S. possesses 2.2 million km2 of high wind potential (Class 3-7 winds) — about 850,000 square miles of land that could yield high levels of wind energy. This makes the U.S. something of a Saudi Arabia for wind energy, ranked third in the world for total wind energy potential.
Let's say we developed just 20 percent of those wind resources — 170,000 square miles (440,000 km2) or an area roughly 1/4 the size of Alaska — we could produce a whopping 8.7 billion megawatt hours of electricity each year (based on a theoretical conversion of six 1.5 MW turbines per km2 and an average output of 25 percent. (1.5 MW x 365 days x 24 hrs x 25% = 3,285 MWh's).
The United States uses about 26.6 billion MWh's, so at the above rate we could satisfy a full one-third of our total annual energy needs. (Of course, this assumes the concurrent deployment of a nationwide Smart Grid that could store and disburse the variable sources of wind power as needed using a variety of technologies — gas or coal peaking, utility scale storage via batteries or fly-wheels, etc).