ISO-NE is responsible for reliably operating New England's 32,000 megawatt bulk electric power generation and transmission system.

The ISO-NE grid does not extend to remote parts of eastern and northern Maine in Washington and Aroostook Counties.

Until the 1970s, the industry consisted of utilities that handled every aspect of providing electricity: generating it, transmitting it and then distributing it to homes and businesses.

During the next three decades, NEPOOL created a regional power grid that now includes more than 300 separate generating plants and more than 8,000 miles of transmission lines.

While the electric power industry's regulated monopolies worked well for generations, by the 1990s the lack of competition provided little reason to improve service, minimize prices or invest in new facilities and technologies.

[citation needed] The FERC created independent system operators, or ISOs, to oversee restructuring on a regional basis.

Its board of directors and over 500 employees have no financial interest in any company doing business in the region's wholesale electricity marketplace.

In this role, ISO New England continues to fulfill its responsibilities, but with broader authority over the day-to-day operation of the transmission system and greater independence to manage the power grid and wholesale markets.

[citation needed] In 2021, the market rules of ISO New England were criticized as inflating the bid prices of renewable energy compared to other sources, resulting in higher consumer costs and more pollution.