Even though the Emancipation Proclamation was made effective in 1863, it could not be implemented in places still under Confederate control. As a result, in the westernmost Confederate state of Texas, nominal freedom came on June 19, 1865, when some two thousand Union troops arrived in Galveston Bay, Texas, at the end of the Civil War, and announced that enslaved Black people in the state were no longer in bondage, although most held in slavery had not waited to be freed. This day came to be known as “Juneteenth” by African Americans in Texas, heralding our country’s second Independence Day and now officially recognized as a national holiday. By the end of the war, millions of enslaved people, some with the assistance of the US Army and the federal government, had seized their own freedom.

https://nmaahc.si.edu/explore/stories/emancipation-proclamation-striking-mighty-blow-slavery/introduction

The 13th amendment has a pretty large loophole that is used constantly.