Years ago, I wrote about my research into the back-and-forth of the 1830s and 1840s in creating the shape of the state of Iowa. I mentioned that I had never seen any proposal of a northern border of 45° from the Mississippi River to the Missouri River, including the southern third of Minnesota and all of eastern South Dakota.
However, as part of an “Iowa 101” course co-sponsored by The Des Moines Register, DMACC, and Graceland University, a foray into the history of Iowa’s northern and western borders that relies almost exclusively on research into Minnesota’s borders does indicate that a straight line that far north was considered at least at one point.
In the end, all the future inhabitants of the land between 43°30′ and 45° N were deprived of their chance to be Iowans, while those east of the Missouri and Big Sioux Rivers were spared the horror of becoming Nebraskans.
The lesson has a curt dismissal of “how far the future Iowa would extend to the south” and I must point out that this certainly wasn’t settled easily, and is among the more famous border disputes in the country.