What class doubled in size during the years between 1900 and 1925?

Between 1900 and 1925, the middle class in the United States doubled in size. This growth was driven by industrialization, urbanization, and an increase in job opportunities, which contributed to rising incomes and a shift in social dynamics. The expansion of education and consumer culture also played significant roles in this transformation. As a result, more individuals were able to attain middle-class status during this period.