EDINBURG — The Museum of South Texas History will host the Sunday Speaker Series Online presentation, “Juneteenth: A History that Unites Us,” featuring María Esther Hammack, Ph.D., at 2 p.m. CST on Sunday on Facebook Live.The presentation will highlight the history of Juneteenth and its relevance to Mexico. Hammack will share under-told stories of people who experienced both U.S. slavery and Mexican freedom as a way to demonstrate how these stories and experiences shape the shared histories of the U.S. and Mexico.Hammack is the Barra Postdoctoral Fellow at the McNeil Center for Early American Studies at the University of Pennsylvania.