The damnyankees had slaves in the north all throughout and after the war. Try again.
Every northern state had either outlawed slavery or had a defined path to emancipation. Exactly zero southern states had anything like it. After the war the northern states passed the 13th amendment.
It is clear that the southern states had no intention of ending slavery and would kill anyone who attempted to interfere.
The few "northern" states that had slavery (if you can count Kentucky and Missouri as "northern") were the ones most sympathetic to the confederate cause. The CSA even tried to count them as members of the Confederacy in spite of the fact that they DIDN'T secede, due to the large number of pro-slavery citizens in those states that were cheering on the CSA's efforts.
The north did not have slaves after the war, slavery was abolished by the 13th amendment. We could do that because the United States of America allows for the abolition of slavery, UNLIKE the constitution of the Confederate States of America, which explicitly forbid abolishing slavery. (by the way, the CSA constitution also said nothing about "states rights" and sometimes even placed MORE restrictions on state powers than the US constitution had)
Try again.
Technically accurate, but highly misleading.
Enslaved people were freed at different period in different areas. The vast majority, contrary to popular belief, were freed by the Emancipation Proclamation as the Union armies advanced.
Quite a few were freed by puppet state governments in the South. TN, AR, LA and possibly others.
Others were freed by state action in MO, WV and MD.
All this was before or at the end of the war.
Only about 50k slaves remained after the war ended, almost all in KY and a couple hundred or so in DE.
These were the only slaves freed after the war ended, by the ratification of 13A in December, 1865. It should be noted that 13A passed Congress before the end of the war.
Also, emancipation was a continuous process, starting only weeks after the war and ending in December, 1865. So to imply that northerners cheerfully kept slaves during and after the war is at minimum historically illiterate.