- 1924
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Company is incorporated and begins acquiring electric utilities in eastern Montana.
- 1927
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Subsidiary formed to develop and explore for natural gas to fuel electric power plants and to build pipelines to transport natural gas.
- 1935
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All subsidiaries merge under a single corporation called Montana-Dakota Utilities Co. (MDU).
- 1945
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A coal-mining operation is acquired to supply fuel for the company's electric generating stations.
- 1948
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Company common stock begins trading on the New York Stock
Exchange on Sept. 20, 1948, with assets of $59 million and
total revenues of $11 million.
- 1951
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Oil boom begins and the company enters into an agreement with an operator to produce its vast reserves of oil in eastern Montana.
- 1968
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Corporate headquarters move from Minneapolis to Bismarck, N.D., to locate management personnel closer to operational territories.
- 1985
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Corporation realigns under new name, MDU Resources Group, Inc., and natural gas transmission operations transferred to new subsidiary, Williston Basin Interstate Pipeline Company.
- 1986
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A growth strategy is launched to expand oil and natural gas reserves and production beyond eastern Montana.
- 1992
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Using its mining expertise, the company enters into the construction materials and mining industry.
- 1997
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Expanding on the company's extensive utility experience, construction services companies are acquired.
- 2000
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Utility operations expand into Minnesota with the acquisition of a natural gas distribution company.
- 2001
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Company sells its coal interests, becoming strictly an aggregate-based construction materials business.
- 2003
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One of the largest natural gas transmission pipeline projects in company history completed.
- 2007
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Merger with large natural gas distribution utility in Washington and Oregon finalized, doubling customer count at the corporation’s utility operations.
- 2008
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Intermountain Gas Company acquisition completed.
Headquartered in Boise, Idaho, Intermountain Gas serves more than 300,000 customers.
©2008 MDU Resources Group, Inc.