MDU Resources Group, Inc. engages in the regulated energy delivery, and construction materials and services businesses in the United States. It operates through four segments: Electric, Natural Gas Distribution, Pipeline, and Construction Services. The Electric segment generates, transmits, and distributes electricity for residential, commercial, industrial, and municipal customers in Montana, North Dakota, South Dakota, and Wyoming; and operates 3,400 miles of transmission lines, 4,800 miles of distribution lines, and 82 transmission and 298 distribution substations. The Natural Gas Distribution segment distributes natural gas for residential, commercial, and industrial customers in Idaho, Minnesota, Montana, North Dakota, Oregon, South Dakota, Washington, and Wyoming; and supplies related value-added services. The Pipeline segment provides natural gas transportation and underground storage services through a regulated pipeline system primarily in the Rocky Mountain and northern Great Plains regions; and cathodic protection and other energy-related services. The Construction Services segment offers electrical and mechanical contracting services, including the construction and maintenance of electrical and communication wiring and infrastructure, fire suppression systems, mechanical piping, and services; transmission and distribution contracting services, comprise construction and maintenance of overhead and underground electrical, and gas and communication infrastructure; and manufactures and supplies transmission and distribution lines construction equipment and tools. It serves manufacturing, commercial, industrial, transportation, institutional, and renewable and government customers, as well as utilities. MDU Resources Group, Inc. was incorporated in 1924 and is headquartered in Bismarck, North Dakota.