What does monopoly mean in us history?

A monopoly is when a single person or business own and controls every part of a industry. In US history, monopolies or trusts began to appear in the 1850's. Men such as Rockefeller, Carnegie, Vanderbilt and Morgan all owned huge monopolistic corporations in oil, steel, railroads, and banking. These corporations enabled prices to drop because the consolidation of production was more economical. On the other hand, they also singularly controlled prices, often to the demise of the commoner. These corporations were eventually broken up by presidents Roosevelt and Taft in the beginning of the 1900's.