Final answer:
Several changes in the 1920s allowed women to enter the workforce, including the return of soldiers from World War I, the increased need for women in professional positions, and the acceptance of women working until marriage.
Step-by-step explanation:
In the 1920s, there were several changes that allowed women to enter the workforce. One major change was the return of soldiers from World War I, which decreased male participation in the labor force and opened up opportunities for women. Additionally, the need for women in professional positions increased, leading to more female college graduates entering the workforce as nurses, teachers, librarians, and more. Finally, it became more acceptable for young women to work until they got married, as their wages could help with family expenses.