How did the people of the United States change the western frontier? Were the changes positive or negative? Explain using proper facts and examples.

The people of the United States changed the western frontier by discovering new resources that they didn't know of in the west, which contributed to the economical growth of the country. They also met new indigenous peoples along the way, and discovered the different types of terrain and geography the western portion had to offer.

high entry costs prevent new producers from entering the market.

explanation:

an oligopoly is a term used to clarify the structure of a particular market, industry, or organization. a market is considered oligopolistic or amazingly focused when it is shared between a few companies.