This Econ-Talk episode on the connection between slavery and racism was quite interesting, but I wish the participants had looked at other countries with a history of slavery, beyond the US and the UK, too, for example at Brazil and Romania.
When we speak about the arbitrariness of borders, we mostly think of the “lines in the sand” in Africa and in the Middle East, drawn by colonial officers. Another striking example were the India-Bangladesh enclaves, a situation that has now been rectified. The world has lost its only third-order enclave, an Indian counter-counter-enclave.
A similar situation exists in Baarle, which is divided between Belgium and the Netherlands in a rather mazy way.