and acquisitions that had been ongoing up to then. Xcel merger However, in 1998, after the failed Primergy merger, NSP merged with New Century Energies of Denver, owner of Public Service Company of Colorado and Southwestern Public Service, to form Xcel Energy. See also St. Anthony Falls Hydroelectric Development - Northern States Power NSP is the successor to several companies that developed hydroelectric power,, starting as early as 1852, at the St. Anthony Falls, Minneapolis, Minnesota. As a result NSP acquired and operated 3 hydroelectric power plants at the falls and just downstream, all built by 1908. One of the plants is still operating. References External links Xcel Energy Additional resources The Historical Records of Northern States Power Company's predecessors are available for research use at the Minnesota Historical Society. Xcel Energy Defunct companies based in Minneapolis Defunct natural gas companies of the United States Defunct electric power companies of the United States Nuclear power companies of the United States Economy of the Midwestern United States American companies established in 1910 Energy companies established in 1910