Why were corporations so successful by the turn of the century?

In America the reasons for corporations becoming so powerful by the turn of the century is the 50 years leading up to it.

After the civil war you had an entire country now dependent on the goods produced by the north. Therefore northern corporations could grow exceedingly well without the threat of southern competition.

Second, the growth in the west. As the country grew westward the ones who really developed it were wealth minded citizens wanting to take advantage of the richest and yet unclaimed parts of the world. As the west grew resources such as gold, oil, coal, iron and other valuable resources became more and more frequent.

Third, the political culture. During this time we had several philosophies that played into the hands of powerful corporations. Laissez-faire which basically means the government doesn't get involved with business, manifest destiny which means that what exists exists to be owned by those who can do the most with it, and social darwinism which was the belief that a person would eventually rise to the point of his greatest potential.

All these things considered you can see why corporations in America during the last have of the 19th century had all the cards handed to them.