The cotton gin, invented by Eli Whitney, greatly increased the efficiency of processing cotton and, ironically, greatly increased the demand for slaves to clear more land, plant, weed, harvest and process the crop.
From William King’s autobiography, “Up to the invention of the cotton gin the seed of the cotton could only be separated from the fibre by hand-picking, and that process was so slow, that it did not remunerate the planter to raise it. But Whitney, who invented the cotton gin, a machine for separating the seed from the fibre, rendered slave labour profitable, quadrupled the price of cotton land and afforded a ready market for the surplus slave raised in the farming states. Cotton became a valuable article of commerce, and found a ready market in Europe. It could be raised in large quantity by slave labour in the US and just as the price of cotton went up the price of slaves went up with it, and a large traffic was thus opened up between the farming and cotton growing states. The surplus slaves raised in Virginia Maryland and Kentucky were collected annually by slave dealers and carried to the cotton and sugar growing states where they were readily disposed of. A traffic was thus carried on between the farming and cotton growing states demoralizing in its nature and evil in practice, it was the means of separating parents and children, brothers and sisters, never to meet again in this world. Marriage was encouraged in the farming states (of the north) for the purpose of raising slaves for the southern market.” (40)
Inventions always have spin-off effects. What are some you’ve noticed?
The Emma Field Novels 
Computers will produce the paperless office:
An early prediction of the paperless office was made in a 1975 Business Week article. The idea was that office automation would make paper redundant for routine tasks such as record-keeping and bookkeeping, and it came to prominence with the introduction of the personal computer. We all heard it. I for one never believed it. Paper would become redundant! NOT!
While the prediction of a PC on every desk was remarkably prophetic, the “paperless office” was not. Improvements in printers and photocopiers have made it much easier to reproduce documents in bulk, causing the worldwide use of office paper to more than double from 1980 to 2000. It is kind of anti-green….. more paper, fewer trees. And so it goes. Old sins cast a long shadow.