MDU Resources Group, Inc. is engaged in regulated energy delivery and construction materials and services business. Its segments include electric, natural gas distribution, pipeline, construction materials and contracting, and construction services. The electric segment generates, transmits and distributes electricity. The natural gas distribution segment distributes natural gas. The pipeline segment provides natural gas transportation and underground storage services through a regulated pipeline system in the Rocky Mountain and northern Great Plains regions of the United States. The construction materials and contracting segment mines, processes and sells construction aggregates crushed stone and sand and gravel; produces and sells asphalt; and supplies ready-mixed concrete. The construction services segment provides a full spectrum of construction services through its electrical and mechanical and transmission and distribution specialty contracting services across the United States.