I was going to make a semi-serious remark about Eli Whitney’s cotton gin making slavery obsolete. A bit of research shows that’s not only wrong, but majorly ironic:

Eli Whitney is most famous for two innovations which later divided the United States in the mid-19th century: the cotton gin (1793) and his advocacy of interchangeable parts. In the South, the cotton gin revolutionized the way cotton was harvested and reinvigorated slavery. In the North the adoption of interchangeable parts revolutionized the manufacturing industry, and contributed greatly to their victory in the Civil War.