"The Age of Big Business" is a history of how businesses changed from small, competing businesses to large corporations that controlled major portions of or all of an industry. Since the book was written in 1919, it was fascinating to see how the various industries have changed from post-Civil-War to post-World-War-I to now.

Chapter One compared 1865 to 1919 in terms of technology and business. Chapter Two gave an overview history of the discovery and business of oil and described how "the first great American Trust," the Standard Oil Company, was formed.

Chapter Three gave an overview history of the major development and business of steel and how Carnegie Steel Company was formed. Chapter Four gave an overview history of the invention, development, and business of telephones and how the American Telephone & Telegraph Company was formed.

Chapter Five gave an overview history of the development of public utilities. Chapter Six gave an overview history of the development and business of agricultural machinery and talked about McCormick's inventions and his three main competitors in that business.

Chapter Seven gave an overview history of the invention, development, and business of the automobile and talked about Henry Ford. .