In the last several decades, teen clothing has become an independent industry – from retail stores advertising the latest fashions to Instagram models forming the new trends with each post. This wasn't always the case, though. Long before the '90s birthed the denim oddity that was JNCO jeans, and even before Seventeen ran its inaugural issue in 1944, "teen" was barely a word in the common vernacular. In the early 1900s, high school clothing trends were essentially smaller versions of whatever was worn by adults. So, how did teen style manage to define 20th-century fashion? Perhaps accessibility – such as the wave of shopping malls in the 1980s – played a pivotal role.