As the industry matured, huge multi conglomerate oil companies
were created. There were oil rights, leases, drilling, marketing, and
product development that were involved in bringing products to market.
The demand for oil increased steadily as nations were emerging as
industrialized countries. It seemed overnight, that the coal industry
was replaced by the petroleum industry.
Since petroleum is a non-renewable resource, new areas needed
to be explored. The leaders in the petroleum industry were the
Americans. The companies soon realized that oil was an international
product. Nations like Saudi Arabia, Venezuela, Indonesia, and Russia
contained vast resources, while other countries in Europe and North
America used these resources. The birth of these multinational
companies, were referred to as the "The Seven Sisters." These
petroleum companies included Exxon, Gulf, Texaco, Mobil, Socal, British
Petroleum and Shell, had influence throughout the world from the mid
1900's to the end of the 1960's.