KeySpan Corporation, now part of National Grid USA, was the fifth largest distributor of natural gas in the United States. KeySpan was formed in 1998 as result of the merger of Brooklyn Union Gas Company (founded 1895 by merging several smaller companies) and Long Island Lighting Company (LILCO). 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. KeySpan had its headquarters in Brooklyn, New York, USA and employed 9,700 people.
In February 2006, National Grid USA, a wholly owned subsidy of National Grid plc of the United Kingdom, announced that it had agreed to buy KeySpan for $7.3bn (£4.1bn) in cash, the deal being subject to regulatory approval and endorsement by the shareholders of the two companies. In 2007 the National Grid plc announced the acquisition of KeySpan Corporation.
KeySpan received a 100% rating on the Corporate Equality Index released by the Human Rights Campaign starting in 2004, the third year of the report.