What Is Juneteenth?

 Here's a very solid summary of what Juneteenth is.

TL;DR: Slavery ended via the Emancipation Proclamation and more so the 14th Amendment. The White South refused to acknowledge the legitimacy of these twin actions and refused to emancipate their slaves, especially in Texas. Texas was the last Confederate state to surrender, and resistance lasted longer there.

If anything, Juneteenth is a celebration of the collaboration between Black advocates and Federal power to insure that freedom was a universal condition. The "Second Founding" of the country from 1861-1876 created a "new birth of freedom." 

That's worth a holiday.