true, but steam driven tractors didn’t come into use until 1890s and a successful cotton harvester was not invented until the late 1920s. So by your criteria, slavery might have lasted into the 1930s.
Slavery was replaced by Share cropping as practiced in some places it was not much above slavery. Tractors and other mechanical farming ended that. So in a rough sense slavery lasted till the 1930s.
I get what you mean, but steam traction engines had existed since the 1850s and probably in solid usage by the 1870s.
And there were other great advances. Such as Cyrus McCormick’s reaper and John Deere’s steel plow. The Industrial Revolution included much of what we think as just “agricultural”.
Slavery is heinous. So is tyranny. We have a great deal of the latter right now; yet, nobody seems ready to lift a finger in order to stop it. What happened 180 years ago doesn't have the urgency of what we face right now in our Nation.