By the early 1920s, many industries had begun to create modern organizational structures.
Companies were split into divisions with different functions, such as sales, marketing, and accounting.
To run these divisions, businesses needed to hire managers.
Managers freed executives and owners from the day-to-day running of the companies.
The managerial revolution in companies created a new career – the professional manger.
The large numbers of new managers expanded the size of the middle class.
Because so many companies were relying on technology, qualified engineers were also in very high demand.