Triple Assassination in 1865, Alternate History

This comes from the Lincoln Assassination thread in which it assumes that the conspirators were successful in killing Lincoln, Seward, and Johnson. A poster stated:

Had this happened, what about American History would have turned out differently? Which Presidents definitely/almost certainly/possibly would never have been elected due to the time shift? How would other things have changed?

I’ll start it off:

  1. Garfield not killed in 1881. The election would have been that year and the previous President is still in office.