How did John D. Rockefeller create a monopoly?

He took out all of the other oil industries and made no competition. He was the only oil industry.

Example: If there is gas station A and B on the same street. Gas station A sells gas for $1 and B sells for $2. Everyone goes to A and B cannot buy any more gas because they get no customers/sales. Gas station A takes out all of the other gas stations and then raises the price to $2 and everyone has to buy it from A.

a. because the u.s. was the leading with the most technology, economy, etc. also was teamed with other allies witch boosted the economy and materials to improve technology and use it.