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KeySpan was a northeastern United States energy utility formed by the 1998 merger of Brooklyn Union Gas and Long Island Lighting Company and acquired by National Grid in 2007.

Last updated August 24, 2026

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Overview

KeySpan Corporation was a regional energy utility headquartered in Brooklyn, New York. The company was created in 1998 through the combination of Brooklyn Union Gas Company and Long Island Lighting Company, commonly known as LILCO. The merger brought together a long-established natural-gas distributor serving New York City and a major Long Island electricity utility. Following the transaction, the combined business briefly used the name MarketSpan before adopting KeySpan. The company’s principal activities were the distribution of natural gas and the provision or operation of electricity infrastructure in the northeastern United States. Its gas operations ultimately extended beyond New York. In November 2000, KeySpan acquired Eastern Enterprises, adding Boston Gas Company, Colonial Gas Company, Essex Gas Company, and EnergyNorth Natural Gas in New Hampshire. The transaction also brought ServicEdge Partners, an unregulated Massachusetts provider of residential heating, ventilation, and air-conditioning equipment installation and services, into the broader group. Through this expansion, KeySpan became one of the largest natural-gas distributors in the United States, ranking fifth nationally according to contemporary descriptions. KeySpan also had an important connection with Long Island’s electricity system. It operated the Long Island Power Authority’s electrical grid, infrastructure that had previously been associated with LILCO before LIPA assumed ownership of the utility system in 1998. This left KeySpan with a combination of regulated gas-distribution operations, energy infrastructure services, and electricity-system operating responsibilities. The company’s corporate history reached back through its predecessor organizations. Brooklyn Union Gas originated as the Brooklyn Gas Light Company in 1825 and took the Brooklyn Union Gas name after a series of mergers in 1895. Its expansion led to prominent Brooklyn headquarters, including a building at 180 Remsen Street designed by architect Frank Freeman and completed in 1914, followed by a 13-story headquarters at 195 Montague Street in 1962 and a later move to One MetroTech Center. LILCO supplied the Long Island component of the merged enterprise. In February 2006, National Grid USA, a wholly owned subsidiary of the United Kingdom-based National Grid plc, announced an agreement to acquire KeySpan in an all-cash transaction valued at $7.3 billion. The purchase required regulatory approval and shareholder support. National Grid announced completion of the acquisition in 2007, ending KeySpan’s existence as an independent listed energy company and incorporating its operations into National Grid’s United States business. KeySpan employed approximately 9,700 people at the time described in contemporary reference material. Beyond its operating businesses, KeySpan received recognition for workplace and inclusion policies. The company achieved a 100 percent rating in the Human Rights Campaign’s Corporate Equality Index beginning in 2004 and continued to receive that rating during the period covered by the reference material. The KeySpan name also survives in historical place branding, including KeySpan Park, although the company itself no longer operates as an independent brand.

History

KeySpan’s history combined the development of two major New York energy companies: Brooklyn Union Gas Company and Long Island Lighting Company. Brooklyn Union Gas traced its origins to the Brooklyn Gas Light Company, established in 1825. After a series of combinations with smaller gas businesses, the company adopted the Brooklyn Union Gas name in 1895. The business expanded alongside Brooklyn’s population and industrial growth, requiring increasingly substantial corporate facilities. A headquarters at 180 Remsen Street was designed by Brooklyn architect Frank Freeman and completed in 1914. In 1962, the company moved into a new 13-story headquarters at 195 Montague Street, and around 1990 it relocated again to One MetroTech Center. The other principal predecessor was Long Island Lighting Company, or LILCO, which supplied electricity on Long Island. In 1998, Brooklyn Union Gas and LILCO merged to create a new energy company. The combined organization initially operated briefly under the name MarketSpan before settling on KeySpan. The merger created a diversified regional utility with natural-gas distribution as its central business and electricity-related infrastructure responsibilities inherited from the Long Island operation. A significant expansion occurred on November 8, 2000, when KeySpan acquired Eastern Enterprises. The purchase added several natural-gas distribution subsidiaries, including Boston Gas Company, Colonial Gas Company, Essex Gas Company, and EnergyNorth Natural Gas in New Hampshire. It also added ServicEdge Partners, an unregulated company focused on residential HVAC equipment installation and services in Massachusetts. This acquisition extended KeySpan’s geographic reach from its New York base into New England and strengthened its position as a large northeastern gas distributor. KeySpan’s electricity role was shaped by the creation and development of the Long Island Power Authority. LIPA took over the Long Island electric system that had previously been part of LILCO in 1998, while KeySpan remained involved as operator of LIPA’s electrical grid. Thus, the company’s post-merger model combined gas distribution, regulated utility infrastructure, and selected unregulated energy services rather than relying solely on electricity generation or retail supply. By the 2000s, KeySpan was described as the fifth-largest natural-gas distributor in the United States. Its headquarters remained in Brooklyn, and reference material places its workforce at approximately 9,700 employees. The company also received recognition for its inclusion policies, earning a 100 percent score in the Human Rights Campaign Corporate Equality Index beginning in 2004. KeySpan’s independence ended through a major acquisition. In February 2006, National Grid USA, a wholly owned subsidiary of National Grid plc of the United Kingdom, announced that it had agreed to purchase KeySpan for $7.3 billion in cash. The transaction required approval from regulators and endorsement by shareholders of the relevant companies. National Grid announced that the acquisition was completed in 2007. KeySpan consequently became part of National Grid’s United States operations and ceased to exist as an independent listed energy company. The former corporate name continued to appear in historical references and infrastructure-related branding, including KeySpan Park, but no longer represented a standalone utility corporation.

  • 2007

    KeySpan becomes part of National Grid

    [1]

    National Grid completes the acquisition, ending KeySpan’s status as an independent company.

  • 2006

    National Grid announces acquisition agreement

    [1]

    National Grid USA announces an agreement to buy KeySpan for $7.3 billion in cash, subject to required approvals.

  • 2004

    Corporate Equality Index recognition begins

    [1]

    KeySpan begins receiving a 100 percent rating in the Human Rights Campaign Corporate Equality Index.

  • 2000

    Eastern Enterprises is acquired

    [1]

    KeySpan expands into Massachusetts and New Hampshire through the acquisition of Eastern Enterprises and its gas-distribution and service subsidiaries.

  • 1998

    KeySpan is formed

    [1]

    Brooklyn Union Gas and Long Island Lighting Company merge to create the company that becomes KeySpan, initially using the MarketSpan name briefly.

  • 1895

    Brooklyn Union Gas name emerges after mergers

    [1]

    Following combinations with smaller gas companies, the Brooklyn Gas Light organization adopts the Brooklyn Union Gas name.

  • 1825

    Brooklyn Gas Light Company is established

    [1]

    The predecessor that later became Brooklyn Union Gas begins operations as the Brooklyn Gas Light Company.

Products and positioning

Regional regulated energy utility and northeastern natural-gas distributor

  • Utility service

    Natural-gas distribution

    KeySpan’s core business was the distribution of natural gas to residential, commercial, and other customers in the northeastern United States. Its network expanded substantially after the Eastern Enterprises acquisition, which added gas utilities in Massachusetts and New Hampshire to the company’s New York operations.

  • Electric utility infrastructure · 1998

    Electricity-grid operation

    Following its merger with LILCO, KeySpan operated the Long Island Power Authority’s electrical grid. The company’s role was principally associated with operating and managing infrastructure rather than owning the Long Island utility system after LIPA took it over in 1998.

  • Energy services · 2000

    Residential HVAC installation and services

    Through ServicEdge Partners, acquired with Eastern Enterprises, KeySpan participated in an unregulated Massachusetts business supplying residential heating, ventilation, and air-conditioning equipment installation and related services.

Brand decisions

  • 2006

    Agreement to sell KeySpan to National GridM&A

    Background

    National Grid pursued KeySpan as a way to expand its United States utility operations, while KeySpan agreed to an all-cash acquisition subject to regulatory and shareholder approvals.

    Action taken

    National Grid USA agreed to acquire KeySpan for $7.3 billion in cash.

    Aftermath

    After completion in 2007, KeySpan ceased operating as an independent company and its businesses were incorporated into National Grid.

    Acquisition value. $7.3 billion (Announced February 2006; completed 2007)

  • 2000

    Acquisition of Eastern EnterprisesM&A

    Background

    KeySpan sought to expand its regulated natural-gas footprint beyond New York and add related energy services in New England.

    Action taken

    KeySpan acquired Eastern Enterprises, including Boston Gas, Colonial Gas, Essex Gas, EnergyNorth Natural Gas, and ServicEdge Partners.

    Aftermath

    The transaction broadened KeySpan’s northeastern operating base and helped establish it as one of the largest natural-gas distributors in the United States.

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