Women were able to hold a more prominent role in the workplace following the passing of the 19th Amendment. With the ability to work alongside men, they were able to receive jobs now. However, many didn't hire women because of their limited mindsets on their work ethic.
Many jobs would be filled in by women in the factories during WWII. Many men were sent to fight the Axis and the Reds overseas, and we needed people to manufacture our goods for the war and at home. Seeing as how women were able to get jobs by then, they filled in.
For a long time, they were just seen as temporary work, and were expected to give up their jobs when the men returned. A little chauvinistic, but such was the troubled time back then.