Incorporated in 1901, Northern States Power Company-Wisconsin is an operating utility that is engaged in the generation, transmission, distribution and sales of electricity in northwestern Wisconsin and in western Upper Peninsula of Michigan. It purchases, transports, distributes and sells natural gas to retail customers. Northern States Power Company-Wisconsin provides electric utility services to more than 248,000 customers and natural gas utility services to over 104,000 customers. It maintains an electric production and transmission system and owns subsidiaries, such as United Power and NSP Nuclear Corporation. The company is a wholly owned subsidiary of Xcel Energy, which serves electric and natural gas customers in Colorado, Michigan, Minnesota, New Mexico, North Dakota and South Dakota.