KeySpan Corporation was the fifth largest distributor of natural gas in the United States. KeySpan was formed in 1998 as a result of the merger of Brooklyn Union Gas Company (founded 1895 by merging several smaller companies) and Long Island Lighting Company (LILCO), and briefly operated under the name MarketSpan following the merger.[1] On November 8, 2000, KeySpan acquired Eastern Enterprises, Eastern's natural gas distribution subsidiaries including Boston Gas Company, Colonial Gas Company and Essex Gas Company; Eastern's unregulated businesses including ServicEdge Partners, the largest unregulated provider of residential HVAC equipment installation and services in Massachusetts; and EnergyNorth Natural Gas in New Hampshire.[2][3] It also was the operator of the Long Island Power Authority's electrical grid, which had previously been part of LILCO before LIPA took it over in 1998. KeySpan had its headquarters in Brooklyn, New York, USA and employed 9,700 people.[4]
In February 2006, National Grid USA, a wholly owned subsidiary of National Grid plc