What were two techniques entrepreneurs used to create monopolies

Horizontal and vertical integration.

Explanation:

The monopolies in America were created using both horizontal and vertical integration. Horizontal integration means that those powerful companies would buy other companies that were “weaker”, this would reduce competition. Vertical integration is when a company buys another company that operates one section of the supply chain. So the company controls the unit economics of the product and control the profit margin.

it made them more prductive and efficent but with the change of polcies less and les got into the navy