Though the southern Confederacy had been effectively vanquished 2 months earlier, it wasn’t until Union forces occupied an area of the former slave states that slavery could effectively be abolished. June 19th marks the day when the furthest frontier of the former Confederacy, Texas, was under the protection of the United States. On that day a formal declaration of the end of slavery (General Order Number 3) was made by General Gordon Granger who was in command of the District of Texas in 1865; unfortunately, it wasn’t until some years later that many enslaved Americans achieved their freedom – see the story of Henrietta Wood (https://en.wikipedia.org/wiki/Henrietta_Wood). Connecticut soldiers were among the U.S. troops that occupied the newly liberated District of Texas including the 29th and 31st Connecticut Infantry – both black units.
CT has archival materials that relate to the abolition of slavery and even the history of Texas…
Yale’s Slavery Miscellaneous Manuscripts collection, 1780-1865 – https://archives.library.wcsu.edu/caoSearch/catalog/mssa-ms-0717
Yale’s Thomas W. Streeter Collection relates to the history of Texas – https://archives.library.wcsu.edu/caoSearch/catalog/beinecke-wa498
And a search of “abolition” in general – https://archives.library.wcsu.edu/caoSearch?q=abolition&search_field=all_fields