Soo with the incorrect history of the civil war in other spouts

Court House - Soo with the incorrect history of the civil war in other spouts i have some questions. Why is slavery only focused on for the southern states when every state had it? Why is only the African American portion focused on when the north had Irish slaves that were arguably more "expendable" as they were cheaper and more readily available with England hating the Irish anyway. Why did some states, union states mind you, maintain slaves during the civil war and after until the 13th amendment was ratified. If you're gonna speak on some speak on all and cover it thoroughly, not just for narrative sake.