PJM History
PJM Interconnection began in 1927 when three utilities, realizing the benefits and efficiencies possible by interconnecting to share their generating resources, formed the world’s first continuing power pool. It has since grown to serve over 67 million people across all or parts of 13 states and the District of Columbia.
1927
Pennsylvania Power & Light, Philadelphia Electric Company, and Public Service Electric and Gas Company form the Pennsylvania – New Jersey Interconnection, creating an integrated power pool.
1956
Baltimore Gas and Electric and subsidiaries of General Public Utilities join the power pool to create PJM Interconnection.
1962
PJM installs its first online computer – an analog computer for automatic generation control.
1965
Potomac Electric Power Company joins PJM as its sixth member.
1968
PJM’s first digital computer is installed to run PJM’s energy management system.
1970
PJM moves its headquarters from Philadelphia to its current location in Valley Forge, Pennsylvania.
1981
Atlantic City Electric and Delmarva Power join PJM, bringing membership in the power pool to eight.
1993
PJM begins the transition to an independent organization with the formation of the PJM Interconnection Association to administer the power pool.
1996
PJM launches its first website.
1997
PJM becomes an independent organization and opens membership to non-utilities. An independent Board of Managers is also elected.
1997
PJM administers its first bid-based energy market.
1997
The Federal Energy Regulatory Commission approves PJM as the nation’s first fully functioning independent system operator, or ISO.
2002
PJM becomes the nation’s first fully functioning regional transmission organization, or RTO.
2002
Allegheny Power and Rockland Electric join PJM.
2004
American Electric Power, Commonwealth Edison and Dayton Power & Light join PJM.
2005
Duquesne Light and Dominion join PJM.
2006
The PJM Board approves its first 15-year regional electric transmission plan.
2011
American Transmission Systems, Inc., a transmission affiliate of FirstEnergy, and Cleveland Public Power join PJM.
2012
Duke Energy Ohio and Duke Energy Kentucky join PJM.
2013
East Kentucky Power Cooperative joins PJM.
2018
Ohio Valley Electric Corporation joins PJM.