I just don't see how that is possible considering the political leanings of the Dakotas at the time circa their admission. Seems to me that they were slightly more favorable to the Democrats.
The Dakotas were Republican strongholds in the nineteenth century, settled mainly by northern WASPs and German Protestants- the hard core of the GOP. McKinley whipped Bryan in North Dakota in 1896 and 1900. Bryan carried South Dakota in 1896- by a miniscule margin, with support from the depressed Black Hills. But McKinley kicked his ass in 1900, and South Dakota voted continuously Republican from that election through 1928.