Steamboats were invented by Robert Fulton in 1807. They were supposed to make shipping more efficient and carrying messages over water faster. They revolutionized water travel, especially once the Erie Canal was created.
Cotton Gin: 1807
Telegraphs were very important to society. They made communication really, really fast, and nobody had to carry messages anymore. They also made more jobs, as there had to be people on both the sending and receiving ends who knew Morse Code.
Power Mill: 1814
Railroads were a faster way to ship things over land and a more comfortable alternative for passengers than stagecoaches. They got food, coal, and commodities quickly overland to wherever they were wanted.
Interchangeable Parts: 1798
Eli Whitney invented the cotton gin as an additional resource for the textile mills. It was a machine that separated the cotton fibers from everything else so that it could be spun into cloth. It made textile making more efficient, but it made the demand for slaves higher, as they could spin more cloth and therefore needed more cotton.
The power mill was invented by Frances Cabot Lowell. It was a mill run by water power so that it could spin cloth much faster than if it had been spun by hand. He used young women and girls to work the machines so he didn't have to pay them as much, and many of them enjoyed the freedom of the mills.
Interchangeable parts were also invented by Eli Whitney. He invented them to make fixing rifles easier, as before him each one had been completely unique. This was a revolutionary invention that made mass-producing rifles much easier, and now interchangeable parts are used in everything.