MDU Resources Group, Inc., a member of the S&P MidCap 400 index and the S&P High-Yield Dividend Aristocrats index, is Building a Strong America® by providing essential products and services through its business lines, including utility companies Cascade Natural Gas Corp., Intermountain Gas Co. and Montana-Dakota Utilities Co.; natural gas storage and transportation pipeline-related business WBI Energy, Inc.; construction materials and contracting business Knife River Corporation; and construction services business MDU Construction Services Group, Inc. For more information about MDU Resources, see the company's website.