Eversource Energy (formerly known as Northeast Utilities) is a publicly traded, Fortune 500 energy company headquartered in Hartford, Connecticut and Boston, Massachusetts, with several regulated subsidiaries offering retail electricity and natural gas service to more than 3.6 million customers in Connecticut, Massachusetts and New Hampshire.Following its 2012 merger with Boston-based NSTAR, NU has more than 4,270 circuit miles of electric transmission lines, 72,000 pole miles of distribution lines, and 6,459 miles of natural gas pipeline in New England.On February 2, 2015, Northeast Utilities and all its subsidiaries rebranded themselves as "Eversource Energy".