NuStar Energy, [1701 - 1799] W 44th St, Sioux Falls, SD 57105, US

Doing business as NorthWestern Energy, NorthWestern Corporation is one of the largest providers of electricity and natural gas in the Upper Midwest and Northwest. It serves more than 628,500 customers in Montana, South Dakota and Nebraska. Approximately 375,000 customers use the company s electric resources and 253,500 use the company s natural gas services. Classified as a mid-sized utility by most industry standards, the company s service territory size is one of the largest in the United States. NorthWestern Corporation is headquartered in Sioux Falls, S.D.