Upper Missouri was organized in 1957 to serve transmission needs of rural electric cooperatives in eastern Montana and western North Dakota. Today, Upper Missouri provides service to 11 distribution cooperatives, 6 in eastern Montana and 5 in western North Dakota. The 11 Member Systems serve 77,714 meters to farms, ranches, homes, and businesses in 37 counties, representing over 54,762 square miles.

Upper Missouri sources power from two major suppliers, Western Area Power Administration (WAPA) and Basin Electric Power Cooperative. The majority of the power, 96% is sourced from Basin.

Upper Missouri has 192 metering points, serves as the Southwest Power Pool (SPP) meter agent and is a transmission owner in Midcontinent Independent System Operator (MISO).

Upper Missouri  is now a 1538 MW system.  Sales decreased 1.33% in 2020 due to the oil / gas slowdown and pandemic. Upper Missouri is projecting steady but more modest growth in the 10 year forecast.

The headquarters facility for Upper Missouri is located in Sidney, Montana which is the county seat of Richland County.  The area ranks at or near the top of all Montana counties in a number of agriculture and other production areas.  It ranks second in oil production in the state and its livestock center is ranked sixth. The area also offers great recreational opportunities to relax in the “great outdoors” with many activities such as hunting, fishing, camping, hiking, golf, and boating.