Excerpt from the National Museum of African American History and Culture:
On “Freedom’s Eve,” or the eve of January 1, 1863, the first Watch Night services took place. On that night, enslaved and free African Americans gathered in churches and private homes all across the country awaiting news that the Emancipation Proclamation had taken effect. At the stroke of midnight, prayers were answered as all enslaved people in Confederate States were declared legally free.
But not everyone in Confederate territory would immediately be free. 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, enslaved people would not be free until much later. Freedom finally came on June 19, 1865, when some 2,000 Union troops arrived in Galveston Bay, Texas.