On the Invention of the Teenager

From the Online Etymological Dictionary:

teenager
derived noun from teenage (q.v.), 1941. The earlier word for this was teener, attested in Amer.Eng. from 1894, and teen had been used as a noun to mean "teen-aged person" in 1818.

From The Phrase Finder:

"America discovered the teenager in the 1940s, or, perhaps more correctly, the American teenager invented herself and himself in the 1940s. In 1947, the 'Encyclopaedia Britannica' identified 'teen ager' as a new word that was coined in 1944, while American Speech included 'teen-ager' in 'Among the New Words' in its April 1945 issue, with an earliest citation of 1944. 'Teen' was not new; several years earlier, Carl Ed has launched his highly successful comic strip 'Harold Teen,' which was adapted for the movies in 1928. While 'teen-age' was used at times in the 1930s (American Speech in 1935 included a usage - 'The dress is probably slinky and suitable for the teen-age group,' while 'Time' magazine of February 22, 1937, wrote of the concern of German parents for keeping 'their teen-age son of daughter out of one of the Hitler camps for young people'), it did not gain momentum until the 1940s." "Flappers 2 Rappers: American Youth Slang" by Tom Dalzell (Merriam-Webster Inc., Springfield, Md., 1996).

TEENAGER - noun. someone in their teens. Originally US: formed from teenage , and confirming the status of the pre-twenties as a force to be reckoned with (and often patronized) in the second half of the 20th century. TEEN - noun. a teenager. A usage anticipated in the early 19th century (title: "Advice to the Teens; or, Practical Helps to the Formation of Character," I. Taylor ), but in modern times mainly US. From "20th Century Words: The Story of New Words in English Over the Last 100 Years" by John Ayto (Oxford University Press, New York, 1999).

Essay from Art Times (November 2006):
"How Hollywood Invented the Teenager" by Henry P. Raleigh

Excerpt from Dr. Michael Platt's "The Teenager and the West".