Massachusetts is perennially locked in competition with its West Coast rival (see No. 1) for attracting green entrepreneurs, but it can pretty easily claim clean-tech king of the East. It won federal approval for the nation's first offshore wind project and more are on their way with the upcoming sale of 164,750 acres of federal water off the coast of Massachusetts and Rhode Island.

In 2012, Massachusetts certified 106 LEED building projects, making up 13.4 million square feet. That put it at No. 4 for the US Green Building Council's Top 10 states for LEED in 2012.

With some of the nation's best colleges within its borders, Massachusetts is rich in what may be clean tech's most precious resource: ambitious and creative, young minds.