1. On September 20, 1889, North Dakota officially became a state, alongside South Dakota, as the 39th and 40th states to be admitted to the Union.
2. In 1930, the town of Rugby, North Dakota declared itself to be the "Geographic Center of North America," based on calculations by the US Geological Survey. A monument was erected to mark the spot, which still draws visitors today.
3. September 20, 1956 saw the opening of the Garrison Dam on the Missouri River in central North Dakota. The dam is one of the largest earthen dams in the world and provides hydroelectric power, flood control, and irrigation for the region.
4. On this day in 2000, North Dakota's current governor, Doug Burgum, made headlines as the co-founder of Great Plains Software, a Fargo-based company that was sold to Microsoft for $1.1 billion.
5. September 20, 2016 marked the unveiling of the $52 million Heritage Center expansion in Bismarck, North Dakota. The new wing of the State Historical Society of North Dakota's flagship museum features interactive exhibits, artifact displays, and a large theater.