(I was always offended, as a child, by all the forms with an entry for "race"; I've been away for long enough that I had forgotten all about it before this thread)
Is it really? Compared to how long people have been competing along tribal lines, 150 years is less than negligible.
(yes, there is tribalism here too —Sneetches will be Sneetches— but the tribalism is at least along slightly more subtle lines than melanin content)
[0] on occasion a very few of us manage 40'000 km/h. Past Performance Is Not Indicative Of Future Results
Among other changes, the Original Constitutional 3/5 of a person language got deprecated.
It starts by talking about "persons", but the right to vote was still reserved for "male inhabitants". Women's suffrage (19A) was a half century in the future, and at the point I emigrated from the Old Country, the ERA still had not been ratified. Haven't checked to see if you all have ratified it since.
Edit: I suspect the reason the Civil Rights Movement was such a big deal in the 1960s is that folks looked around and said to themselves "100 years of Reconstruction, and we're still lynching?"