PNM Resources, Inc., through its subsidiaries, engages in the energy and energy-related businesses in the United States. It operates through Public Service Company of New Mexico (PNM) and Texas-New Mexico Power Company (TNMP) segments. The PNM segment is primarily involved in the generation, transmission, and distribution of electricity. It generates electricity using coal, natural gas and oil, nuclear fuel, solar, wind, and geothermal energy sources. As of December 31, 2018, this segment had owned or leased facilities with a total net generation capacity of 2,102 megawatts; and owned 3,206 miles of electric transmission lines, 6,067 miles of distribution overhead lines, 5,885 miles of underground distribution lines, and 255 substations. It also owns and leases office and other equipment, office space, vehicles, and real estate. The TNMP segment provides regulated transmission and distribution services. As of December 31, 2018, this segment owned 997 miles of overhead electric transmission lines, 7,151 miles of overhead distribution lines, 1,260 miles of underground distribution lines, and 122 substations. It also owns and leases vehicles, service facilities, and office locations throughout its service territory. The company serves approximately 782,000 residential, commercial, and industrial customers, as well as end-users of electricity in New Mexico and Texas. PNM Resources, Inc. was founded in 1917 and is headquartered in Albuquerque, New Mexico.