June the Nineteenth is Emancipation Day in many states in North America. It is the oldest nationally celebrated commemoration of the ending of slavery in the United States from 1865.
Of course we English made the slave trade illegal in 1802, 1807 and again in 1833. In practice it was illegal in England from 1772 but not formerly enshrined in law till much later. Of course that’s nothing compared to the forward thinking Japanese. In 1588 Toyotomi Hideyoshi ordered all slave trading to be abolished.
The UN formerly banned slavery in 1948 as part of the Declaration of Human Rights.
Juneteenth is also a fine example of a portmanteau. No, not the travelling case but a fusion of two words and their meanings into one.