Both of those dates also...

Both of those dates also coincided with times when there were spikes in racist violence. The 1910s saw the revival of the Ku Klux Klan, which had dissolved in the 1870s. The 1960s saw major pushbacks against the civil-rights movements and was the period when some Southern states added the Confederate battle flag (not the Stars and Bars) to their state flags. It is not entirely coincidental that these upsurges in racist activity occurred around the 50th and 100th anniversaries of the Civil War, a war fought by the South to keep black people unfree.