Happy 131st Birthday, South Dakota (And North Dakota) Posted by John Axtell Date: November 02, 2020 68 Views Today is Statehood Day for both North and South Dakota, the 131st anniversary of both becoming states. Both were admitted to the Union on Nov 2, 1889, as the 39th and 40th states – but no one knows which is the 39th and which is the 40th. That’s because President Benjamin Harrison intentionally mixed up the papers before signing them so that the order of signing would be a mystery. According to legend, Harrison had Secretary of State James Blaine cover both proclamations with a sheet of paper before they were signed, then shuffled them – reportedly saying “they were born together, they are one, and I will make them twins. North Dakota and South Dakota were originally part of the Dakota Territory, established in 1861 and including parts of Montana and Wyoming.