Lower natural gas prices and regional environmental initiatives are leading natural gas-fired generators to provide a greater portion of the electricity in the northeastern United States. The Northeast is a combination of two regional transmission organizations: the Independent System Operator of New England (ISO-NE) and the New York Independent System Operator (NYISO). Both of these systems have seen a dramatic shift since 2001 away from petroleum- and coal-fired generation to predominantly natural gas-fired output in 2012 and 2013.

via Northeast grows increasingly reliant on natural gas for power generation – Today in Energy – U.S. Energy Information Administration (EIA).