I think all Americans and those who study the country should know something about what James Loewen and other historians call the nadir period of American race relations. It is incredible what kind of things were done.
The era of Reconstruction after the Civil War was relatively cordial between blacks and whites (though Indians were getting massacred), but around 1890 things changed. Younger people who had not lived through the Civil War had grown up. Immigrants from Europe and China, who obviously knew nothing of the war, had arrived. The Republican Party stopped being the party black people could get something out of. This period has only gone away bit by bit, at times such as WW2, the Civil Rights movement (plus of course the Cosby Show ;)), and leaves its legacies to this day.
After 1890, the way history was perceived began to change. No longer was the Civil War about slavery but about states’ rights, as told by many monuments put up during this period. The best-selling book and most popular movie of all time in the US is Gone with the Wind, which is a revisionist fiction that millions of Americans take as true. Woodrow Wilson, a white supremacist, segregated the federal government as best he could. All manner of legal forms of discrimination were enacted at federal, state and municipal levels (“Jim Crow”) which excluded blacks from voting, land and housing while sending others to prison. White labour unions forced blacks out of jobs. The Ku Klux Klan rose and lynchings became common in many places. At its peak in the mid-1920s, the KKK was national, with branches all over the US. Thousands of these places became sundown towns. Sundown towns are towns, sometimes with populations in the thousands, usually relatively wealthy, which at some point ethnically cleansed the town of blacks (along with Jews or Chinese if there were any) in a kind of pogrom. In many cases, they remain sundown towns.
Furthermore, to justify all of this to maintain their position on top, white people began more than before to believe in theories of racism. We began to hear about “good breeding”, the idea of genetic superiority. This is of course the time when Social Darwinism and scientific racism were gaining ground. White Americans gave it a major boost. Stricter immigration laws were enacted. Did you know they practiced eugenics in the US? The government began sterilizing those of “dubious stock”, such as isolated rural people, the poor and those with low IQ-test scores. The standard IQ test used in the US and the Scholastic Aptitude Test or SAT come from this period, from the eugenics movement. These developments in fact inspired Hitler’s eugenics programme. American eugenicists applauded. However, when the concentration camps were discovered and the logical conclusion of completely disenfranchising an entire group was understood, eugenics died in the US.
All this is absent from high school history textbooks, yet it explains a considerable amount about the modern US. Perceptions of race or similar categorization (eg. Muslims in a Christian nation) influence immigration policies and, increasingly, security policies. And today’s racism is still largely based on old hypotheses about racial superiority and the tests to prove it.