History Of North Dakota By kallieaerickson Dec 1, 1889 North Dakota became the 39th State North Dakota Dec 15, 1890 Sitting Bull was assassinated. Sitting Bull Dec 1, 1911 State flag was designed North Dakota State Flag Dec 1, 1938 First hard-surfaced highway completed across state Highway Dec 1, 1979 Oil boom began in western part of state; sunflowers became second largest cash crop; 23 counties eligible for disaster assistance due to spring flooding Oil Boom Jun 1, 2011 Flooding forced thousands to evacuate Minot and Minot areas. Flooding in Minot.
