Fallacious yet widespread and documented beliefs courtesy of Wikipedia.
Abraham Lincoln's Emancipation Proclamation of January 1863 did not immediately free all American slaves. The Proclamation pertained only to areas within rebelling states that were not under Union control. Since those states did not recognize the power of the federal government, most slaves were not immediately freed as a direct result of the Proclamation. Regions in the South that were under Confederate control when the Proclamation was issued ignored its dictum, so slave ownership persisted until Union troops captured further Southern territory. Immediately affected regions were Tennessee, southern Louisiana, and parts of Virginia. It was only with the adoption of the Thirteenth Amendment in 1865 that slavery was officially abolished in all of the United States. Thirty-six of the United States recognize June 19 as a holiday, Juneteenth, celebrating the anniversary of the day the abolition of slavery was announced in Texas in 1865.