UIL Holdings Corporation, through its subsidiaries, operates in the regulated utility businesses. It is involved in the purchase, transmission, distribution, and sale of electricity for residential, commercial, and industrial purposes in the southwestern part of the State of Connecticut. As of December 31, 2011, the company served approximately 324,000 electric customers. It has electric transmission lines that consist of approximately 101 circuit miles of overhead lines and 28 circuit miles of underground lines; owns and operates 27 bulk electric supply substations with a capacity of 1,894 megavoltampere (MVA) and 17 distribution substations with a capacity of 87 MVA; and has 3,293 pole-line miles of overhead distribution lines and 132 distribution conduit-bank miles. The company also engages in the transportation, distribution, and sale of natural gas to approximately 374,000 customers in Connecticut and western Massachusetts. It has natural gas systems that comprise approximately 4,284 miles and 738 miles of distribution pipeline in Connecticut and Massachusetts; operates and maintains various gate stations; and owns and operates 2 liquefied natural gas plants. The company was founded in 1899 and is headquartered in New Haven, Connecticut.