These charts, from the Pew Internet and American Life Project, really need no commentary and certainly won’t come as a surprise.
Of course “classifieds ads websites” is another way of saying Craigslist, which had 42.2 million unique visitors in March 2009, compared with 53.8 million total unique visitors to classified sites.
For an equally dramatic chart of US newspaper ad revenues (not just classifieds) over the past three years, visit Alan Mutter’s blog.