On this day in 1889 North Dakota and South Dakota became the 39th and 40th states to be admitted into the Union, so today marks their 120th birthday. Here are a few quick facts on the founding of the Dakota Territory and their admittance as states. For more information on their history, check out the Website of the Library of Congress:

The first European explorers, Louis Joseph and François de La Vérendrye, entered the region in 1742 and 1743. At that time, at least eight Native American tribes populated the vicinity including the Mandan, Arikara, Kidatsa, Assiniboin, Crow, Cheyenne, Cree, and the Dakota (Santee Sioux).

From 1868 until the late 1880s, controversy over the location of the capitol divided citizens of Dakota Territory. Northerners named Bismarck their capitol in 1883, while Southerners created their own constitution that year selecting Pierre as the capitol. In February 1889, shortly before statehood was granted, congressional legislation officially divided the Territory.