The POD for preventing the assassination of Lincoln and for that matter Garfiled, McKinley and Kennedy is better security. I would have a federal officer guarding the entrance to the box. He does not let Booth in. Booth dies in a shot out with that officer. The way Lincoln was evolving on the issue of votes for Blacks. I could see the 14th Amendment barring discrimination in voting based on skin color or previous condition of servitude. Lincoln has a good working relationship with Congress. He remains in charge of Reconstruction. There is no Tenure of Office Act and of course no impeachment. This is one of those short lived PODs. In 1868, Grant is elected. He brings his commitment to civil rights and his corrupt cronies with him. So starting on March 4, 1869, OTL returns.