Library of Congress acquires entire Twitter Archive. Slate runs an article explaining why historians are so interested. We have entered a blackhole when it comes to personal communications. But what about other forms of communication- Facebook, etc.? Twitter is not heavily used by younger people- why Tweet when you have a Wall! While Twitter may be the fastest growing Social Media it is telling that the heaviest demographic of Twitter visitors is 35-49 years old (According to NielsonWire).