In 1830, Peter Cooper, a well known and established inventor managed to invent and construct the first steam locomotive. He even bought a land as to have space where the test it and run it to be assured that it came out as planned. Once he introduced his invention on the market, everyone was fascinated and immediately saw the enormous potential this invention had. Not all of the country was connected through major waterways, so lot of parts were cut out. The steam locomotive though was moving on the railroads, thus on land, and it was able to reach every part of the country if the infrastructure was set up. This invention resulted in large scale migrations toward the west, easier trade and transportation of raw materials and goods, rapidly leading to economic boom.
However, if we had to point to a particular moment, we might point towards 1920, as this was the year in which more Americans were living in cities than in the countryside for the first time. One of the innovations that had the greatest influence on this shift was the introduction of the assembly line.
1: It means that one government controls the whole population of people and the only way they can do that is to be voted in.
2: The best characteristics of a democraitc is that the rules for the country are direcly elected by the people. which means it is the government for the people by the people.