In the years 1900-1920 the fashion was very different from the fashion we have today. At that time many young working girls didn't like to to wear feminine (girly) clothes. As you might know girls in these times wore long non-revealing clothing to show the respect they for themselves. Many young working boys wore dandies which were old kind of suits used to impress or to look decent. Also to work and be presentable.
This topic did change over time because teens needed more types of clothing (more styles). They wanted to explore more and create more styles in teen fashion.