– The word ‘teenager’ wasn’t really needed – there were adolescents (aged around 12-15) and there were young adults.
– In the past, many people below the age of 19 were already working, in apprenticeships, or even married with children of their own. This declined after the 1800s in the UK and USA as young people were required to stay in school longer and longer.
– By the 1900s, the quality of life was increasing. With more technology around the house, there was more leisure time and young people had more opportunities to do typical ‘teenager things’ like socialising, listening to music, going to the beach or for a barbecue.
– The wars of the 20th century disrupted family life. In 1914-1918 many young boys in Europe were sent off from home to fight, so they were forced to grow up quickly. In 1939 – 1944 there were attacks directly on London and other British cities, and many children were directly involved, looking after younger brothers or sisters when their parents died, or working in industry (for older teenage boys) or on farms (for girls). They couldn’t go back to being children once the war ended! The Vietnam War in the 1960s changed things forever for American kids – boys could be sent off to die once they got older, girlfriends could lose their boyfriends forever, so young people wanted to enjoy as much freedom as possible in their teenage years.
Here are some links, for further reading: