Historical footnotes
I grew up in the Midwest, too. There was no doubt about it having been a Union state during "the recent unpleasantness", yet it became, for a time, a cradle of renewed KKK activity.
The second Ku Klux Klan was founded in 1915 by William J. Simmons, an ex-minister and promoter of fraternal orders; its first meeting was held on Stone Mt., Ga. The new Klan had a wider program than its forerunner, for it added to “white supremacy†an intense nativism and anti-Catholicism (it was also anti-Semitic) closely related to that of the Know-Nothing movement of the middle 19th cent. Consequently its appeal was not sectional, and, aided after 1920 by the activities of professional promoters Elizabeth Tyler and Edward Y. Clarke, it spread rapidly throughout the North as well as the South. It furnished an outlet for the militant patriotism aroused by World War I, and it stressed fundamentalism in religion.
Professing itself nonpolitical, the Klan nevertheless controlled politics in many communities and in 1922, 1924, and 1926 elected many state officials and a number of Congressmen. Texas, Oklahoma, Indiana, Oregon, and Maine were particularly under its influence. Its power in the Midwest was broken during the late 1920s when David C. Stephenson, a major Klan leader there, was convicted of second-degree murder, and evidence of corruption came out that led to the indictment of the governor of Indiana and the mayor of Indianapolis, both supporters of the Klan.
[Source: The Columbia Encyclopedia, Sixth Edition; 2001 at Bartleby.com - emphasis mine]
There's a documentary film, too.
In the second largest city in the state, the public schools were not integrated until a full ten years after Brown vs. Board of Ed., and that required a Federal court order (as did so many other cities in the "anti-slavery" North). The neighborhoods took a lot longer, and only after another implicitly racist phenomonon you may have heard of: "white flight".