Which part off the state had the greatest number if aircraft facilities during World War 2?​

America's manufacturers in World War II were engaged in the greatest military industrial effort in history. Aircraft companies went from building a handful of planes at a time to building ... No war was more industrialized than World War II. ... The American aircraft industry was given impetus at the early part of the war

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.